Saturday 27 May 2017

MEASUREMENTS: SMSL iDEA USB DAC / Headphone Amp (ESS Sabre ES9018Q2C + XMOS XU208)

In 2015, ESS revealed its latest generation of DACs at the CES show. One of the interesting new products revealed was the SABRE9018Q2C, a tiny 5mm x 5mm SoC claiming very high audio quality out of an integrated DAC/headphone amp operating with low power along with the ability to decode a wide range of sample rates.

I was contacted by ZugZugOrc on Computer Audiophile to have a look at a recently released USB DAC he wanted to buy for some measurements based on the above chipset. So we made an arrangement where he sent the package to me to have a look at and subsequently after I'm done, I would send it off to him to use :-). Thanks Zug for the opportunity!

Here's the device - the SMSL iDEA (can be found on Amazon for ~US$86 currently), a mini USB powered "stick" based on the ES9018Q2C "audiophile-quality" mobile DAC capable of accepting up to 32/768 and DSD512!

SMSL stands for  "ShuangMuSanLin" Electronics Company based in Shenzhen, China. I was sent the black one, but the device is also available in red.

As you can see, the box has the "Hi-Res Audio" logo on it which means it has been certified through the Japan Audio Society. It comes with 3 USB adaptor cables to connect the device to standard USB-A, microUSB (OTG cable for a typical Android phone or tablet), and USB-C devices.

As for the DAC itself, it feels sturdy enough in a metal enclosure, and tiny measuring 6mm x 60 mm x 16mm. On one side is a 3.5mm headphone jack and the other side a female microUSB. On the top is a low profile volume switch which controls the volume independently of the OS volume setting, so when I first plug it in, it defaults to a lowish amplitude setting. You have to push the volume + button a few times to get it to 100% (I didn't check how many clicks - probably at least 10) and also make sure the computer / streamer is set at 100% to truly get the highest output. I assume the volume control is done digitally. I like this, I can send bitperfect PCM and DSD to this DAC, and just use the hardware buttons instead of fiddling with software controls.

This is a fairly low-power DAC that can be used with mobile devices like cell phones and tablets provided enough power is available. Apart from the low power DAC/amp chipset, the other half of the equation for energy efficiency is the USB microcontroller chip. This device uses the XMOS XU208 (datasheet here), a new "second generation" Xcore200 device (I believe the specific device here is the 8-core, 128KB, ~500MIPS version, 1000MIPS with dual issue). It is this device that allows communication at 32/768 and DSD512 with the host USB2.0.

Before I get to measurements, remember that previously, I had reviewed and measured a number of products using ESS DACs. The 2013 Oppo BDP-105 used the ES9018, in 2014 I had a look/listen to the AudioQuest Dragonfly 1.2 based on the ES9023, PonoPlayer in 2015 with the ES9018K2M,  Light Harmonic Geek Out V2 also in 2015 is based on the ES9018AQ2M, and most recently I had the preview of the Oppo Sonica DAC and its ES9038Pro.

Each one of these ESS Technology DACs share the "HyperStream" architecture. If you look around, although ESS Technology tends to hold full datasheets close to their chest, we see that these DACs typically incorporate an oversampling anti-imaging reconstruction filter with programmable parameters, jitter reduction (by an onboard asynchronous sample rate converter), and then fed into the noise-shaped sigma-delta converter. For those interested, check out Martin Mallison's Rocky Mountain 2011 presentation (and more in the company's 2007 SABRE technical paper):

Given this pedigree and what I have seen previously, I certainly have high hopes for the objective output based on the latest and greatest "mobile reference DAC".

As usual, the measurements will be based on my standard setup as follows:
Device (eg. laptop, SB Touch, phone, HTPC) --> SMSL iDEA --> generic 6' phono-to-RCA cable --> Focusrite Forte --> 6' USB cable --> Win 10 measurement computer

Part I: Digital Oscilloscope, Digital Filter, Impulse Response

Here's the 1kHz 0dBFS 16/44 square wave output on the digital oscilloscope with the hardware volume at 100%:

Nice channel balance. Peak 2.73V corresponds to ~2Vrms. No clipping confirmed with 0dBFS sine wave (not shown). The configuration of the Gibbs phenomenon at the edges of the square waves suggest a symmetrical linear phase digital filter.

There she is... Linear phase filter as predicted. It maintains the positive polarity of the original impulse signal.

And here's the "Digital Filter Composite" as used in most of my recent DAC measurements based on discussions with Juergen Reis.

Overall the graph shows a "sharp" roll-off filter with good suppression of imaging above Nyquist. There's about -80dB of suppression between the ~20kHz and the ~40kHz imaging cluster. If you look at the Oppo BDP-105 measurements, you'll see that comparatively, the suppression was stronger with the Oppo - not an audible difference obviously! Also not surprising is that intersample overloading happens with the 0dBFS signal as I have found with almost all DACs these days.

Using a 20-ohm resistor at the output with a 1kHz sine wave playing at a reasonable volume resulted in a measured/calculated output impedance of approximately 0.5-ohms.

I got an inexpensive USB tester to look at current draw from the USB device during use:

With the music paused, the device is drawing 110mA at 5V. As you can see, I have some 16-ohm impedance JVC HA-FXC51B IEM headphones (sound great for the price!) connected to it. At 100% volume playback (extremely loud) while playing Depeche Mode's "Stripped" (might as well use real music off the album Singles 81-98), the current increased to ~210mA peak. It's important to keep these numbers in mind because if you're going to attach this to a phone or tablet, the device will need to be able to supply this amount of current for it to work. As you'll see below, I was able to use this with my Samsung Galaxy Note 5 phone.

For comparison, the Light Harmonic Geek Out V2 (measured here) sucks up 450mA idle, up to 500mA playing back in 100mW (into 16-ohm) mode, and up to 700mA in the 1000mW mode. The AudioEngine D3 (measured here) uses 160mA idle, with 280mA peaks using the above 16-ohm IEM.

Part II: RightMark Tests

Okay, time to run a few comparisons then... Unless noted otherwise, the measurements were obtained with my Surface 3 computer running Windows 10 loaded with the SMSL ASIO driver as found here (2017-04-11 version used).


Okay, check out the line-up. We have the iDEA, PonoPlayer, Oppo BDP-105, TEAC UD-501, and finally the venerable Squeezebox/Logitech Transporter for comparison.

Honestly guys, 16/44 is a piece of cake for any modern DAC capable of hi-res. I feel I have to measure this because it is important given the amount of 16/44 content out there... But finding an anomaly is typically rare and usually "by design" such as the PonoPlayer. The most overt anomaly in the numbers is of course the PonoPlayer and its frequency response resulting from the digital filter setting used by Ayre emphasizing a very short impulse response (but at the expense of ideal frequency domain performance).

As usual, here are a few graphs from the data:

As you can see, the PonoPlayer shows its usual high-frequency roll-off and the slightly higher IMD+N can be seen.

Going into hi-res, this is where we separate the men from the boys...

Not bad at all! This little SMSL DAC is able to demonstrate a very low noise floor on par with much more expensive devices.

Here are the composite graphs:

Overall very nice showing from the iDEA! You can still see a bit of an edge for the much more expensive Oppo BDP-105, TEAC UD-501, and Transporter devices in the IMD+N sweep for example. But man, these are impressive results for such a tiny and inexpensive device!

Quickly, the 24/192 tests... No Logitech Transporter for the obvious reason that the DAC maxes out at 24/96.

Again,the SMSL iDEA achieves very respectable results comparable to much more expensive devices.

Part III: DSD64 / DSD128

I don't measure DSD performance often but over the years it's good to have a peek to just make sure things look and sound right... Here are the results using the 24/192 PCM signal converted to DSD64 and DSD128 using Weiss Saracon.

Basically it looks good. There is minimal difference between the DSD and PCM measurements. Noise floor from 20-20kHz very comparable as per the numerical data indicating DSD playback about just as noise-free as PCM. Notice the slightly higher overall noise level with DSD64 which is a real finding and consistent with the fact that noise shaping is used aggressively with 1-bit quantization. We can see rising noise >20kHz on the graphs for both DSD64 and DSD128; cleaner with 24/192 PCM as expected.

Part IV: Jitter

One would expect jitter to be very well controlled:

Yes. Beautiful 16 and 24-bit Dunn J-Test results from this little DAC! This is what I expect to see with the ESS Sabre DACs. As you can appreciate, explicit claims about "femtoclocks" appear unnecessary for jitter control these days.

Part V:  Comparison between different source devices

Since this is such a tiny DAC which uses low power allowing its use with portable devices, I thought it would be fun to compare the output among the following...
Notice the power LED glowing purplish with the Surface Pro rather than the usual blue. This color tells you that it's working in "ultra" high sample rate mode - PCM 352kHz+. It glows red for DSD playback.
As you can see, I have the little DAC connected from top left going clockwise to: Microsoft Surface 3 Windows 10 using ASIO driver, Squeezebox Touch with EDO plugin, HTPC running Windows 10 Creators Update with native WASAPI USB Audio Class 2 driver, and finally my Samsung Note 5 phone running Android 7.0 "Nougat".

You can find the details of the HTPC (Skylake CPU) build here to check out the hardware in the big black box. Since that post however, I've added a nVidia GTX 1080 graphics card in there!

I had some trouble with the Logitech Squeezebox Touch. Initially the output from the DAC was a noisy buzz but with a few reboots and using EDO Kernel #12, it eventually worked. I noticed a similar issue with Android playing bitperfect through USB Audio Player Pro on the Note 5. I needed to make sure to start the app first, then plug in the device through the microUSB OTG cable in order for it to be recognized and initiated properly.

Despite issues with Linux/Android-based machines, I had no problems at all with the Windows ASIO driver, native WASAPI driver from Windows 10 Creators Update or Mac OS X over a USB-C MacBook.

Here are the measurements at 24/96:

As you can see, both numerically and in graphs, there are simply no differences!

And what about jitter?

Anyone see a difference of significance?!

Heck, to make it even more nasty, how about we run the nVidia GTX 1080 graphics board and Intel i5-6500 CPU full tilt at 100% with FurMark torture test and Prime 95 in the HTPC box?

You likely can't see the details in the image, but FurMark is running at ~200fps, GPU utilization at 100%, GPU temperature 78°C, internal fans going strongly, and I've plugged the SMSL iDEA DAC into a rear motherboard USB 3.0 port closest to the video card for exposure to any electrical/RF noise.

No difference! Not even increase in noise floor... And no anomalies noted at all in the IMD+N overlay graph.

How about jitter?

Nothing different. Surprised? You should be if you follow the typical "audiophile wisdom" expressed at the usual places by the usual people. Sure, I can show computer-generated noise affecting audio output in some situations (for example slightly more noise with this old internal PCI audio card with high load), but it doesn't appear that computer load affects the USB interface to this little DAC. Perhaps the little DAC's internal power regulation circuitry is very much capable of cleaning up whatever noise is there - all without needing to buy any filters or tweaks (which in the tweako-audiophile world likely would cost more than the SMSL DAC itself!).

Part VI: Conclusions

As you can see from some of the pictures above of the different systems I hooked the DAC up to, I had connected my AKG Q701 headphones to check for obvious changes in sound between the different setups. I also subjectively had a listen at times with my trusty Sony MDR-V6, Klipsh R6i IEM, and Sennheiser HD800 headphones and even downstairs with the main system using phono-to-RCA cables.

It sounds excellent as expected, consistent with the objective results. I had a listen to Martin Roscoe's Nielsen: Complete Piano Music, the 2017 remastered Paul McCartney's Flowers In The Dirt (DR12), and selected tracks from Ansermet's The Royal Ballet: Gala Performances (DR12, 2009 remaster). No complaints about the DAC sound. "Unveiled", low noise floor, neutral sounding. As I have heard many times with ESS Sabre DACs, the high fidelity "clarity" of the sound is often described as "clinical" in nature by some listeners. Others might even describe some kind of "digital glare"... The way I hear it, there are some recordings that are just overly bright which I attribute to the album production and mastering rather than the DAC. There are ways to counteract this... For example, a device like the PonoPlayer is based on the Sabre DAC chip as well but when playing 44kHz audio, sibilance and "glare" would not be a problem because of the purposeful high frequency roll-off.

With an output impedance of ~0.5-ohms and good output voltage of ~2Vrms into a high impedance load, volumes achieved with the headphones I tried were certainly good enough for my use ranging from "loud" to "very loud" (remember, don't go deaf!). However, the ESS 9018Q2C's integrated amplifier section is rated at 49mW into a 32-ohm load, THD 0.1%. This means that if you have low impedance and low sensitivity headphones, there might not be enough current to drive these demanding loads. Within reason, this should not be a problem since this DAC is meant for mobile applications. A device like the Light Harmonic Geek Out V2 (previously measured) with 1000mW (into 16-ohms though) might satisfy those who want more gain and of course get a dedicated headphone amp if you need even more than that (for example to power planar magnetic 'phones)!

By the way, for Apple MacBook users, I can confirm that the DAC works well connected with the USB-C adaptor. It shows up in the "Audio MIDI" panel without fuss and allows sample rates to 32/768kHz.

So, what have we learned?
1. Objective quality is excellent with this device. It measures very much like the Oppo BDP-105 in fact! That's actually quite amazing and I was certainly impressed when I first saw the results I was obtaining; I had already had a listen and suspected the results would be excellent.

2. Again, the digital source did not matter to the analogue output from this DAC whether it was a desktop type computer, Squeezebox Touch, laptop or cellphone. No evidence of noise issues even comparing the output from a cell phone with that from a desktop computer running a nVidia GTX 1080 graphics card at 100% load!

3. Excellent jitter suppression from the ESS DAC is again shown. Not that jitter has been a significantly audible issue for years with decent modern equipment...

4. If you're going to use this device with a portable source - cell phone, tablet, etc... double check compatibility given the 100-200mA current draw. I can confirm that it works with my Samsung Note 5 cell phone (see item 5 next). I was also able to get it to work with an old first-gen iPad using the 30-pin Camera Connect Kit! Unfortunately I didn't have the Lightning CCK to try with my wife's iPhone 6 or iPad Air 2.

5. The one main concern I have - issues with Linux-based devices including Android. I suspect there's something not quite right with the "plug-and-play" UAC2 drivers interacting with this device. What happens is that when I first plug the device into a Linux/Android machine (like the Pi "Touch", Note 5, Squeezebox Touch), the power goes on and the device goes into some kind of inappropriate starting state. When I try to play something, the output is an annoying buzzing noise with the audio being played at a very low volume. What I have to do is start the app (eg. USB Audio Player Pro on the Note 5) or configure the music program (eg. for the Pi "Touch" with piCorePlayer, tell Squeezelite to use "USB audio" and Output setting to "front:CARD=v12,DEV=0" in my case then save and reset), then unplug and reconnect the DAC. It works fine afterwards.

Of course the above issue is annoying and should not be like this. SMSL, please have a look into this! Might need to update the firmware for improved Linux compatibility? I have sent an E-mail to SMSL and will update if I hear back...

As I close off, I think this is another example of how as technology continues to mature, we're seeing higher and higher audio quality out of less and less expensive devices. Something like this SMSL iDEA - powered off USB even from a cell phone, in such a small form factor, easily measuring within striking distance of much more expensive DACs would not have been possible a few short years ago! And with the flexibility to play back at PCM 768kHz and DSD512 sample rates as well. All for less than US$100!

Speaking of the PCM 768kHz and DSD512 sample speeds, if you look at the ESS information about the ES9018Q2C, they actually only mention that the DAC is capable of 384kHz and DSD256 (11.2MHz) in the product brief. I wonder if the higher sample rate is just undocumented in the publicly available information or if the XMOS USB microcontroller might be doing downsampling before feeding the DAC. I'll have to take a look at this another time with my oscilloscope. I'd be interested if anyone has insight into this. In any event it's not like there's actual content at 768kHz or DSD512/22.4MHz to really benefit from these ultra-high sample rates (upsampling in JRiver 22 to these high sample rates sounds great)!

Ahhh, portable audiophilia... With Rebecca Pidgeon, The Raven (24/88 Bob Katz remaster) audiophile standard of course... :-)
The other day, I was listening to the set-up above while doing some paper work. Very impressive sound indeed through the 300-ohm Sennheiser HD800. As it is, these 102dB/V headphones sound loud enough with excellent bass extension. Given the measurements, it would literally take headphones like these in a quiet room to appreciate the remarkable accuracy of this DAC! There is obviously no way I would be able to appreciate the nuances this DAC can provide walking around the neighbourhood with headphones on.

Given the state of the hype these days, I suppose some might wonder about the importance of MQA and obviously the fact that this device doesn't support it. Clearly, I'm not the guy to talk to since I don't believe MQA makes much difference other than as a partial lossy compression scheme, provides questionable benefits with no evidence of actual value beyond a few testimonies.

But remember that the XMOS Xcore200 microcontroller inside does have 8 threads, 128KB of SRAM, what looks like 4Mbits (512KB) flash memory (Winbond 25X40) and something along the lines of 500 to 1000 MIPS of processing power. This appears to be much more powerful than what's in the AudioQuest Dragonfly Red/Black series (Microchip PIC32MX). I wonder how much processing speed is needed to implement even a single MQA unfold to 24/88 or 24/96 and if this level of processing speed from XMOS is enough...

As I said a couple weeks ago, digital audio truly is democratizing high-fidelity output to the point now where judged purely on ability to reproduce high resolution sound, there's no need to look much further than a device like this. Of course that doesn't mean I'll be trading out a nice desktop DAC because I still want balanced XLR output, there's value in having other digital inputs like S/PDIF, and a nice desktop device like the TEAC UD-501 or Oppo Sonica DAC just looks nice on the audio "rack" :-). I certainly do not discount the importance of non-utilitarian factors.

Thanks again ZugZugOrc for the opportunity to take this little DAC out for a spin! Originally the plan was that I test it out then send it on to him in the UK... Well, considering just how well this device worked - amazing fidelity in such a small portable package -  I decided to just buy it off him and use it myself! It would also make a great gift at some point for potential audiophile friends :-).


Looking over the news feed this week, Munich High End 2017 has passed with a few announcements but it doesn't seem like there was much actually new. The What Hi-Fi? reports seem quite thorough showing pictures of the "latest and greatest" generation of gear.

Of the things on display, the Mag-Lev turntable certainly is eye-catching (began as a Kickstarter project). I wonder what kind of wow and flutter measurements it achieves as it seems to wobble a bit based on the videos I've seen of it in operation. Other measurements like noise level and distortion would be very interesting given what must be quite a strong magnetic drive unit. I wonder if the low-voltage moving magnet cartridge would pick up distortions and would a moving coil cartridge be even more susceptible as they tend to have even lower voltage outputs. Also, good to know there's a UPS system for potential power failures... Stability in operation also would be important for accidental knocks on the floating platter I imagine! Will be interesting when it's released and we read some reviews on this device in daily use.

Hope you're all enjoying the music as usual... Also remember, stay sane and rational :-).

ADDENDUM (June 3, 2017):
As requested, here's the RightMark frequency response curves across various low impedance/resistance loads:


  1. Can it be used as just a DAC to connect to a separate headphone amp?

    1. Yup.

      Just connect the phono output to the input of a typical headphone amp.

  2. A test such as this is important because it shows that DACs are getting cheaper and better all the time, and have reached audible perfection. Quite simply, even better measured performance will not be audible.
    What I am still keen to see is an affordable desktop DAC with (preferably) balanced outputs, volume control, and multiple inputs: usb, plus two optical and coaxial inputs each, to cover all possibilities. There are many with one optical and one coaxial each, but that is really one short in many situations (e.g. tv, disc player, and a streamer like the Chromecast). I have tried hard, but I can find none, other than at the expensive end of the market.

    1. Yes. That's indeed the take home message!

    2. I just got SMSL AD18 as a birthday gift, and I can tell you it sounds great. It has a separate headphone amp, which is cleaner than the speaker one, although not as powerful. It sports a Texas Instruments DAC, it has a remote control, a quite ok LCD screen, 2 optical inputs (1 of which shares the coax input), 1 line-in, 1 micro USB in, and bluetooth apt-x 4.2 with a great range. It goes soooo loud, that I can easily blow my Klipsch RP-160M if I wanted to. Just to put it into perspective: the volume goes up to 59, and I usually have it set at 12 for casual listening in my livingroom - all my music is normalized by Foobar, so it´s lowered to 89 db. If I wanted my neighbours "come-a-knocking", 20 would be enough, at this level no conversation is possible. I never pushed them higher than that, it´s just crazy how loud (and clean) this little 2.0 receiver can get. When watching Youtube videos streamed via Xiaomi Mi Box 3, connected through the optical cable, I have to lower the volume down to 8-9, that´s how insane this is. Keep in mind, as well, my speakers are one of the most efficient bookshelf speakers available, your mileage might vary. As for the headphones, I own a pair of Koss Porta Pro-s, and they sound clean and punchy, the highs are much cleaner now. I guess high-end headphones would benefit more, but that´s what I could afford so far. And they go loud, as well (the volume of hp amp goes only up to 30, which is plenty for my needs, 10-11 is as far as I would go). So far, highly recommended for the current price of 137 euros.

      PD: Thanks to reviews like yours, one could make their mind and buy this little gem called Idea, which I just did. Thank you very much for the in-depth review and measurements, I ordered it on sale for 68 euros a couple of days ago, now it goes for 76, good thing I read this post on time! Greetings from Spain.

  3. It works with foobar on desktop?

    1. Yes.

      Foobar, get the WASAPI plugin and it'll work great with Windows 10 Creators Update native driver.

      Alternatively, get the ASIO drivers from SMSL. Get the ASIO plugin for Foobar. Enjoy bitperfect as well.

      I don't bother with foobar for DSD these days. JRiver does a great job and will upsample to your heart's content...

  4. how does this smsl idea stack up with dragonfly bl/rd

    1. I'll tell you in a few weeks :-).

      Working on that...

    2. I look forward to your comparison, I saw your measurements page for the dragonfly 1.2 and it indicates that it's using a linear pass filter. For the dragonfly red/black, the marketing materials state that they employ minimum phase filters. I wonder how different they'll sound to the smsl subjectively.

    3. I've been listening to the DF Black last couple nights. It sounds quite good. Very similar to the iDEA actually with sensitive headphones.

      For me the whole linear vs. minimal phase filter thing isn't a big deal subjectively. Proper 44/48kHz music will already be low-passed and should not show ringing in playback. The nasty stuff that rings would already sounds nasty regardless of filter setting! :-)

    4. I haven't heard the dragonfly black, and I've only heard the red connecting to an external amplifier, I've also heard it briefly with the MQA update, but that was right after listening to Vinyl on the $50,000 Hifiman electrostat system which ruined everything else.

      Will you be doing a measurements page for the Dragonfly Black? Subjectively, I prefer minimum phase filters although they smear more in time. Doesn't 44.1/48khz already have pre-ring hard coded into the samples from the Brickwall filter required when downsampling or even when sampling? So even with a minimum phase reconstruction filter, there'll still be some pre-ringing present.

    5. Also a comparison to the Audioengine D3?

    6. Will compare Audioengine D3, Geek Out V2, SMSL iDEA, and Dragonfly Black in the next couple weeks...

  5. When I can't hear an appreciable difference on three different systems the quality of a $79 Behringer UMC 204HD balanced out and a $4000 Cary DMS-500 you know the train has reached the station.

    Just an incredible value for all the format support it offers.

    1. Yes Matt. Eventually it will be about "value" and "features".

      As much as some old-school audiophiles and various writers might not want to talk about it or face it, the idea of sound quality as a adjudicator will be technically irrelevant. I'm sure many will continue to use fancy adjectives, "origin stories" of companies and hi-fi heroes, and possibly entertaining stories in subjective reviews to justify what they "hear".

      I think we're well on our way to a time when products belonging to the "high end", high price tag arena will be viewed simply as luxury items of various forms. Already, IMO, many audiophiles recognize that high price tag actually doesn't buy anything that sounds better - just as much likelihood that it performs technically worse.

    2. I suspect you're correct about the response from the high-end subjectivists. And that's a damned shame.

      The true message should be that you can spend most of your time & budget worrying about speakers & room treatment/correction. And that message might encourage more people into the hobby...

    3. >I think we're well on our way to a time when products belonging to the "high end", high price tag arena will be viewed simply as luxury items of various forms.

      A good analogy: you don't buy a fancy Swiss watch for its accurate time-keeping. For that, you'd do as well with a $10 digital watch from the drugstore. You buy a Rolex for all the things signified by that bit of conspicuous consumption strapped to your wrist.

  6. What's the output impedance at 20 Hz? Basically I wanna know if there are coupling capacitors.

    For example the Benjie X1 has a 2 Ohm Zout at 1 KHz, but it is AC coupled, and the caps they used are really small:

    Another way is to just run a rightmark test with low impedance load and check the frequency response graph.

    1. I'll have a look at 20Hz when I get a change HyG.

    2. Looking forward for the results.

    3. I'm also very interested of confirming if doesn't use coupling capacitors.
      Thanks for the amazing measurements and review!

    4. See ADDENDUM.

      No evidence of frequency response change with 20/50/100-ohm loads. Doesn't look like coupling caps at play. Output impedance ~0.5-ohms.

    5. Thank you.

  7. FYI, I contacted the manufacturer and they said it supports lightning cable Apple devices with camera kit.

  8. Does the LED light change colour at all depending on if DSD or PCM is being played back or with different sample rates?

    As for the ESS Dac's max sample rate, I can't remember where I read this but apparently I read that the DAC in the dragonfly's can do up to 768khz, it's just the micro-controller can't handle those sample rates. I've been trying to find it.

    I can't remember what else I was going to add, but for now this was an interesting article and I am tempted to buy one.

    1. Hi LY,
      The LED only has 3 colors as documented:

      Blue - standard PCM to 192kHz
      Purple - PCM 352kHz and above
      Red - DSD

      Would be nice to have a few others I guess but not really needed IMO.

      The new Dragonflies have ES9010K2M(?) for the Black, and ES9016K2M(?) for the Red. The specs I've seen still list them as up to 384kHz. Obviously the microcontroller in the DF's only goes to 96kHz so no biggie.

    2. Thank you for the information regarding the Led's, I didn't see that on the product page and that's useful to know.

      A competing product I was looking at was the nextdrive spectra, but the LED seems to stay blue and it goes up to DSD256/352.8khz which is sufficient as I don't know of DSD512 or 768khz commercial recordings, but for those with Jriver or HQplayer like you, it leaves the option of upsampling with high quality filters.

      Another competing product using the same or similar chip is the space key dac which has a really cool oled display.

      I hope other manufacturers can implement something similar, that is such a good idea.

      Is there a method I can use to contact you? I've been reading your blog for a while and have only just figured out how to comment. Thanks for your replies btw.

    3. Hey LY.
      That's an interesting little USB DAC as well - very similar guts and I do like the little OLED screen which explains the price differential. Interesting that they're not pushing it to DSD512 and 768kHz. Again I wonder if this SMSL is actually converting at such high input rates or if it's being down converted to DSD256/384.

  9. I can attest to the SMSL IDEA working with the standard Apple camera kit on the iPhone 6. It works well the Tidal app with HIFI settings and the iPhone music player. It doesn't, however, like to function properly when I open the Onkyo HF player with the HD pack. As soon as I open the app, I get a buzzing noise and cannot play a file whether it's FLACs/MP3s upsampled to DSD or PCM. I even tried disabling any upsampling settings. Disconnecting/reconnecting the DAC does nothing; when I reconnect it with the player still open, the buzzing returns.

    1. Hi Erikson,
      Thanks good to hear about the CCK and iPhone 6.

      Looks like you're running into the same buzzing issue as well. I E-mailed the SMSL folks so hopefully they'll have a look at this.

    2. If you are like me and only use this DAC to play files locally on your Android device, after a few days of tweaking I can recommend this:

      - Install UAPP and launch it. Despite what the developer recommends, this DAC needs the driver to take complete control over the USB before plugging in. As they state in their advertising, it only works within the app. I know, it´s not free, but just pay the lady, you will never look back. From what I can tell their driver works much better than Android's.

      - Plug in the device

      - Check the "Default " option in the pop-up message. I suggest you uninstall any other player like Hiby Music, I have both and the pop-up message kept showing up when the DAC was plugged in, and sometimes this added step prevented the driver to operate, which caused the buzzing. Unless you can disable the autostart option for Hiby Music like I can on my Xiaomi device, you might consider uninstall it altogether, you don´t want any interference in the process.

      - (Optional) Install a little app called USB Host Check (also recommended by the UAPP's developer). In case your Android device lacks the USB host feature or it's not implemented correctly, it will try and rewrite the xml USB Host file, and enable it. To my surprise, mine had to be patched this way for the iDEA to work properly, even though I'd used OTG cables in the past with no issues. The thing is I had to hit "Fix" several times, "Recheck", then "Fix" again for the file to be written. YMMV, but if you get the error message, don't give up easily. From the feedback users gave, on some devices might not be posible, though. If you got to this step, reboot the device and launch UAPP.

      In my case this fixed the buzzing, the DAC is now detected by the UAPP every single time and works great. Unfortunately, I can no longer use it with any other app, not even You Tube. I don´t get the buzzing any more, but no other sound either from any other app except UAPP (only through the iDEA; if I unplug it, everything goes back to normal and I can listen through the speaker or the audio jack). The USB driver is doing its job too well, which in my case is what I prefer, to be honest.

      I hope it helps.

  10. Hey Archimago,

    Thanks for the reply! I was able to get the IDEA DAC to finally work on the Onkyo HF Player on my iPhone after some trial and error. After reading what you did to get proper playback on USB Audio Player Pro on your Android device, I used similar steps . I initiated the HF Player first without the DAC connected, then exited to the iPhone Menu/Home screen with the player still open in the background. Only then did I connect the DAC to the phone. Once I retuned to HF Player, I was able to playback FLAC/mp3 files buzz free, upconverted to 176Khz PCM or High-Precision DSD 5.6 Mhz. If I had connected the IDEA with HF Player directly opened, buzzing noise would have been emitted to my headphones.

    I've been in contact with SMSL via email as well. Their English is hard to comprehend at times. I’ve been emailing them regarding buzzing when playing FLACs upconverted to DSD512 on Foobar2000 (using the Foobar ASIO DSD/SACD plugin). SMSL’s reply: “[to] use DSD, you need to turn up the max volume on your PC. And FOOBAR have a power to be individually occupies a computer device,after you close this program, your original player app will be closed immediately.While you reconnecting this item,the original player will be work again.”

    1. Good that you're contacting them as well. I bugged them again about looking at the blog post and seeing if they can fix this buzzing.

      The "great firewall of China" prevents access to Blogger (and much of the Google family); so they need to access via VPN. Not hard to do, so hopefully they get a chance to read the post and comments...

  11. I can get DSD512 to work on Foobar2000 with Windows 10 Creators Updates but it's also a tedious process:

    1. Open Foobar2000 with the IDEA DAC connected.

    2. Under Preferences -> Playback -> Output, select "ASIO : foo_dsd_asio" in Device dropdown.

    3. Under Preferences -> Playback -> Output -> ASIO, double-click "foo_dsd_asio" to open "ASIO Proxy 0.8.3" dialog box.

    4. ASIO Proxy 0.8.3 settings:
    - ASIO Driver: USB DAC ASIO
    -DSD Playback Method: ASIO Native
    -PCM to DSD Method: SDM Type D (FP64) ; Fs: DSD64

    5. Apply settings and exit preferences, then disconnect/reconnect the IDEA DAC.

    6. Go back to preferences to change the PCM to DSD Method to Fs:DSD512. Your FLACs files should play without a hitch. However, before you exit the player, you should reset the DSD Method to Fs:DSD64, because if you don't the next time you open Foobar and play a file with the IDEA DAC, you will get buzzing.

    1. Wow Erikson.

      Thanks for the tip! Indeed a little tedious but I hope you're enjoying the fruits of your labout :-).

    2. I emailed them a video recording with me going through the steps of upconverting a FLAC file (352Khz, 24-bit) to DSD512 through foobar. I played back the file without following the steps I outlined below(i.e. initially setting the Fs on ASIO Proxy to DSD64). That way I was able to record the buzzing. I captured the audio output from the IDEA to the AUX on my SB X-fi HD Titanium using a line to RCA cable. They also sent me a video which corresponds with steps outlined in the above post ("turn up the max volume..."), but they didn't help though.

      It is unfortunate they can't see this blog, but hopefully they can bypass the block through a VPN.

    3. Nice work!

      I got a reply from SMSL. They have seen the review and acknowledge some compatibility issues and are looking into it... Hopefully we'll see a fix in the not too distant future!

    4. Is this an issue with the W10 CU drivers or did this happen with the XMOS drivers that came with the dac?

  12. Thanks! I'm glad they've acknowledged some of the compatibility issues. If they can fix those issues with a firmware update, it would make the IDEA great value for all its features. For features, I would highly recommend it over the Dragonfly Red I have. Sure, you get MQA rendering with the Red, but I appreciate the ability to upsample my music to rates > 96Khz or convert on the fly to DSD. I also feel it isn't as rugged, I have already scratched the nice red finish after a short drop to the floor :p One thing it has going for it though is its ability to sip very little battery life from my iPhone.

  13. I wonder how it compares to HiFime Sabre 9018 USB DAC. The Massdrop listing puts the SMSL at similar price.

    1. I've got both, can't tell the difference tbh, the idea might be slightly less bright. This is smaller and more compact however the 9018 outputs to optical as well.

  14. I've been using a ES9018K2M based DAC for some time now. I've had more expensive DAC's in the system but honestly there are much better places to invest in sonic performance. The thing I like about these devices are their simplicity: a receiver, a DAC and a pump. My music doesn't miss the lights, dials, power supplies, etc.

  15. Mine keeps just dropping out using iPhone 6. I have to unplug it and re-plug it in to make it work again. It's random and swapped out cables. Where can i contact the manufacturer about this? Has anyone else experienced this? Does your unit get pretty hot?


    1. Hi Ed, contact Kelly here:

      I've already been in touch to discuss the Android/Linux compatibility issue.

      I don't have the Camera Connect cable for the iPhone 6 so alas can't test it for myself. Hopefully the USB power requirements are met!

    2. My unit occasionally drops out on Tidal, but not to the point where it's frustrating. However, my listening sessions are relatively short, 10-15 minutes spurts.

      Mine can get really warm, but I've only noticed this when I upconvert FLAC files to high precision DSD 5.6Mhz with Onkyo HF Player.

    3. Interesting about the heat Erikson. I wonder how much more power is being used when fed high-res like 24/768 or DSD256/512... Will have a peek when I have the chance.

  16. Hello . As 9018q2c rated 49mw@32 Ohm , but the smsl idea says their dac/amp is 35.8mw@32 Ohm . Whats the real output?

    1. The SMSL specs quote the smaller number of 35.8mW into 32-ohms... I'd just go with that.

    2. Whats gonna be the output in 16Ohm , probably my comment was deleted(

    3. Hi Алина,
      Quite possibly a comment was deleted. The spam filter tends to take comments out on occasion inadvertently.

      At 16-ohms, ideally it should be 2x 32-ohms. So somewhere between 70-100mW. However, I suspect it will be current limited and likely will not hit that while maintaining low distortion...

      If I find time, I'll put this back on the oscilloscope with a 16-ohm load and see how much I can drive it before clipping to get a more "real world" view of the power limits.

  17. Could you pretty please review the Schiit Fulla 2? Pretty please??

  18. thank you for your review ! you convinced me to give this a try and I'm expecting great things! Just grabbed the last one from Amazon uk and only 60 quid! based on your review and others I'm hoping I just landed a great deal.

    p.s wait until zeos reviews does a review on the smsl idea you watch the availability suddenly vanish or the price go up 3 fold!

    1. Have fun N Britain!

      Remember to keep the Android buzzing in mind and the headphone power limitations. As a Windows headphone DAC, it sounds great IMO and I can't think of a better deal on something that can handle these kinds of crazy PCM and DSD sample rates to play with!

  19. Bought without knowing the issues and have unbearable buzzing on Note 1 and Note 4 as well. So disappointed.

  20. I fixed the issue of buzzing on android devices. You have to go to developers options an set it to MIDI mode. I guess the fact that it also works when you start the play, you get the buzz, then u pull the DAC and reconnect it it does the same and recognizes it as MIDI. Unfortunately Marshmallow doesnt show the USB options to me when connecting the DAC. Android used to. Does anyone else know how to get the automatic options back?

  21. Shenzen told me to reverse the USB cable - which makes total sense on a symmetrc cable. Real pros there.

    1. Hilarious, can´t wait to see what their response will be to my email now.

  22. This is the email I just sent to Kelly (please DSD guys out there don´t hate me):

    Hello Kelly,

    I get in touch with you to report a compatibility issue. I use the iDEA connected to my Xiaomi Redmi Note 2 phone, and sometimes I get a buzzing noise instead of music. I understand that my device is not compatible, as it is not listed on your database, but it actually works with USB Audio Player Pro most of the time. Sometimes the buzzing comes back, always after plugging into the phone, and even though I somehow managed to circumvent the issue by launching UAPP first, then connect it, the problem doesn´t seem to be gone completely. Sadly I'm not alone, almost ALL Android users who bought it experience the same issues:

    What happens is the DAC is not recognized as an audio interface, so Android detects it as a hard drive or even as a device that needs charging, which increases the current on the bus, therefore we get a buzzing noise instead of sound. Some Android versions have in a submenu inside the UI the appropriate easy-to-access "USB Audio" option, but most don´t, which doesn´t necesarily mean it doesn´t work, it just doesn´t do it AUTOMATICALLY, as in my case. Once switched, it works great, but still, it´s quite annoying and will make for sure the users to give bad reviews, despite its great potential on paper.

    What I´m going to say now may very well be the craziest advice/suggestion you´ve ever received, but maybe you should have taken HiFime Sabre 9018's approach, with its limitations to the well tested USB 1.0 compliance and no more than 96 kHz 24 bit audio. Forget about DSD for now, what people need is RELIABILITY above else, if the Android platform is not mature enough, keep it simple and safe. Compared to the aforementioned device, you still would have had the edge: better design, smaller footprint, and volume control buttons for roughly the same price. Why is it then yours don´t receive the same acclaim? Who cares the chip inside is capable of all those things? Very, very few people need it, most of us appreciate more RELIABILITY over UNCERTAINTY.

    I don´t even know if this would fix the issue, but I checked out the latest xCORE-AUDIO Configuration Utility, and it´s pretty straight forward. As stated on the paragraph 2.2.3 of the pdf manual, I would suggest you (if I may) to change the value:

    # USB Audio class 1.0 enable/disable

    UAC_1_ENABLE = 0

    to "1" instead of "0", create an alternative firmware for those with compatibility issues, and provide a guide to flash the device to downgrade. And from now on sell it in two configurations, "if your phone is not listed, just buy this one", something along those lines. I would have happily payed the same amount of money for a "lesser", but more compatible, pain-free version. This would have made for a great gift, as well, but as I care about the people I give it to, I might look elsewhere, not to mention I don´t want them to constantly call me.

    I don´t know if the issue is on your end, or XMOS´, but unless you try to solve this problem quickly, this device will not have the impact it deserves. You have a golden opportunity to turn this into the go-to portable DAC for the masses, but with no widespread Android compatibility this is hard to imagine, let alone it would defeat its own purpose as a portable device.

    Looking forward to hearing from you, yours trully,


    Keep in mind that I suggest they sell it in both configurations, please don´t misinterprete me. Cheers.

  23. Btw i only found Sony music center to be the only free usb hi res app. What dobu guys use?

    1. This comment has been removed by the author.

    2. Hiby Music.

  24. USB 1.1 firmware from SMSL:

    Please, be warned — you can't reverse to usb 2.0 without original wirmware!

    1. Hello friend, can you reupload the firmware please. or send it to my email

  25. Thanks Chief. Certainly be cautious about using the USB1.1 firmware if it cannot be flashed back to USB2.0!!!

    Remember everyone, this will make the iDEA cap out at 24/96. It's supposed to help compatibility with Android devices. IMO, not recommended unless you truly must have compatibility with certain portable devices and don't mind crippling of the DAC (ie. limited to 24/96, no DSD ability).

  26. After 2 weeks I couldnt get rid of the buzzing. I found USB Midi mode is not enough. Something actived to deny USB audio routing under dev options. So make sure on ur phone it is deactivated as well.

    1. You´re absolutely right, in developer options you must uncheck USB audio routing, and let UAPP do it instead. I found out that Android and UAPP routing sometimes collide in the most nasty way.

  27. Btw Ill buy an OTG hub to feed the device woth power ajd I hope that the hub maybe enables correvt detection from then on . We'll see.

    1. I've already tested iDEA with external-powered USB-hub. Same shit, same buzzing (Samsung Galaxy S7 and some other Android phones). It's a f\w error, I guess. Ugly f\w code, as in many chinese-developed devices.

  28. Hi Archimago,

    Do you know if this amp is capable of line-out/DAC only mode to avoid double amping?

  29. Thank you for this great review, I bought the SMSL iDEA immediately after reading your review!

    I am now using the iDEA as a DAC and feeding its signal into my O2 headphone amp. I am wondering if I should max out the volume of the iDEA (both PC and the DAC itself)? or I should leave some volume headroom for the DAC and let the amp work harder? Which method would provide better results theoretically?

    Thanks a lot!!

  30. Any feedback from SMSL about incompatibility?

    1. Alas other than the firmware discussed above, I have not seen anything new...

  31. I have the same problems with the buzzing sound with the Sabaj Da2 on my android LG G5 (for those of you who are looking into getting the OEAM cheaper option as it's the exact same board it seems). However, the method of playing music first and then connecting the DA2 seems to work in eliminating the buzzing sound... However, I have a hunch(and have read that this might possibly be the case on another forum) that by using this method the dac part is actually bypassed and that only the amp section of the DA2 is activated. CAn someone confirm if this is possible?

  32. Thanks for your review. Bought it after read this.

  33. using adaptor can work normally once take out the Window Surface Pro 4 will shut down
    this is a cause

  34. Wireless optical mouse-this can be a decent decision for the individuals who still like to tap the mouse. best wifi adapter for pc gaming

  35. Thanks Archimago for this excellent review and comparission references.
    My questions are:
    1- Can This IDEA Dac be used as Preamp (as it has volume control) directly to power amplifier?
    2- Can I use a HDMI from my PC to micro USB adapter in the dac?