FiiO K11 R2R DAC: Affordable R-2R desktop DAC & headphone amp. Let's talk about R-2R and euphonic preferences.

It has been more than a year since I last measured or reviewed a DAC!

To be honest, in 2026, DACs are IMO boring from the perspective of expecting any sonic progress when it comes to high-fidelity audio. They are very much a "solved problem" and will not pose any challenge for the audiophile who desires accuracy. Unless there's some new technology to evaluate or must-have features, digital-to-analogue conversion has clearly matured to allow extremely high resolution playback - perceptibly perfect even - within reach of basically everyone in the last decade.

[In the big cultural-level picture, I think we're at the phase now with less expensive products (eg. Chi-Fi) where more than adequate function has been achieved and we're going to be seeing an emphasis on "Design-Driven Innovation" where emotional, symbolic, and esthetic significance become more important with each generation for product differentiation. I think we're already seeing this with the FiiO line-up as I describe related products to this at the end of this post. In time, I suspect this will be an existential threat to many current High-End brands.]

Because of that lack of excitement around evaluating yet another DAC objectively, for more than 6 months now, this FiiO K11 R2R DAC (US$176, Canada link) has been sitting on my table for evaluation! 🙄 I bought this with the plan of using it in my office at the hospital for desktop speaker playback and headphone listening which I'll do after publishing this.

Make sure not to confuse this model with the slightly less expensive FiiO K11 non-R2R DAC (US$145) which uses the Cirrus Logic CS43198 chip. Feature-wise, I think they're very similar and look identical other than the stylized "R2R" stamped on the top of the case.

Okay, let's put this through its paces...

Part III: Topping DX9 "15th Anniversary" Limited Edition DAC & Headphone Amplifier - DSD, S/PDIF inputs, headphone out, pre-out, and AMPT. And the desire beyond Perceptibly Perfect.

With Raspberry Pi 'Touch' streamer showing album art running RoPieee, and the Topping DX9 VU meters playing, this looks quite nice in the audio rack!

Let's finish up with the last installment of the review/measurements for the Topping DX9 "15th Anniversary" DAC (see Part I, and Part II previously). As we have seen up to this point, it's quite a unique looking DAC and the initial PCM measurements over USB2.0 look great as a modern hi-resolution converter. In Part II I noted that there was an issue with the 176.4/192kHz frequency response that Topping was able to correct quickly with a firmware update. I'll be using the latest firmware 1.23 for the measurements here.

Let's continue then to dive in and explore the objective performance with some of the other main features for this DAC.

EARLY LOOK (Part II): E1DA #9039S USB Balanced DAC dongle/headphone amp - DSD and performance under load. A few more words on the "need" for higher DAC fidelity!

Last week, I published Part I of the review/measurements on the upcoming E1DA #9039S USB dongle DAC/headphone amplifier. Already, we've seen that this ESS ES9039Q2M-based balanced DAC produces very clean, high-resolution sound.

As we continue, let's delve deeper into the performance of this little device. We'll have a look at some features like DSD performance and more importantly, let's examine the balanced amplifier output when subjected to headphone-like loads to see how well it performs.

EARLY LOOK (Part I): E1DA #9039S USB Balanced DAC/headphone amp - Super Hi-Res, Tiny Package! Also, let's tweak...

Hey everyone, it's time to have another look at a product from the engineering workshop of Ivan Khlyupin (IVX) at E1DA - the E1DA #9039S:

Notice balanced 2.5mm TRRS phono output.

As you can see, it's a prototype/preproduction (depending on whether the circuit could still change) unit with pen markings on the box for the number "9" to make sure the correct product was sent my way. 🙂

This is the latest iteration of E1DA's line of USB2.0 dongle DACs which includes the E1DA #9038D6K I had a look/listen to in late 2022. As you likely surmised, this update is based on the next generation of ESS Sabre DACs - the low-power, 2-channel, ES9039Q2M, using their sigma-delta Hyperstream IV modulator. The chip specifications list 130dB of dynamic range, -126dB THD and -120dB THD+N. We'll see in a little bit what Ivan has been able to "cook up" in his lab including some performance results. Back in 2022 with the #9038D6K DAC, he had already achieved -120dB THD+N (120dB SINAD) with single-ended output. How much better does it get!?*

As I sometimes do, due to time limitations, I'll split this write-up into 2 portions to present different roles/functions of the device. For today's Part I, let's just focus on the usual look-and-feel as well as using this device as a straight, unloaded balanced DAC. This will give us an idea of the performance capabilities of the ES9039Q2M in the hands of an experienced engineer. Next time we'll examine this device as a headphone amp.

The current anticipated price for this USB DAC/amp is presumably going to be less than US$150; I believe the exact number is still being crunched.

[* Asking how much better in terms of THD+N is of course a different question from "How much resolution does a person need for excellent high-fidelity reproduction?"!]

Retro DIY Headphone Amp - The Audio Amateur, Gary A. Galo design, built by Mitch Barnett circa 1991.

Every once awhile, I think it's fun to try something a little different!

While the vast majority of us audiophiles buy our stuff, as per all tech hobbies at one point, this began with hobbyists in their workshops, basements, and "caves" putting together electronics parts and enthusiast kits with soldering irons making their own stuff. I remember the days in the early '70s as a child when the hi-fi system at home was put together by my dad based on designs he found in the magazines. A time before commercialization of consumer electronics was anywhere like it is today.

With miniaturization and economy of scale, these days, it's more expensive to build one's own components (both time and money) and more than likely the sound quality would not be as good. Of course, there is an element of lasting pride in building something oneself which we can never really capture when purchased with a credit card. Major respect to the DIY guys and gals out there still designing and making their own gear.

So instead of a commercially available product, let's have a look at the device shown above. It's a home-made "prototype" headphone amp lent to me by Mitch Barnett (of Accurate Sound) built on a wooden board (I guess there might be some vibration control with that ;-). He built this something like 30 years ago based on a design published in The Audio Amateur (4/91, predecessor to today's AudioXpress) by Gary A. Galo. For a bit of background on The Audio Amateur, check out this thread and post from Palustris.

REVIEW: E1DA #9038D6K Dongle DAC / Headphone Amp (Part II): Headphone Amp Power, DSD, Subjective Impressions, AMPT & Perfectionistic Tweaking!

A great sounding music listening station! (Samsung Galaxy Tablet, Drop+HiFiMan HE-4XX, classic Jacky Cheung cantopop.)

Okay friends, today we continue with Part II of the discussion on E1DA's #9038D6K portable DAC/headphone amp. Please refer to Part I last time for the general overview of DAC performance which already tells us about the PCM resolution of the device. The data from last time shows that for the price and size, this unassuming dongle is one heck of an accurate, high-fidelity, high-resolution digital-analogue converter.

This time, let's move forward with exploring other areas not yet discussed. Specifically, let's focus on resolution when under headphone-like loads, look at DSD performance characteristics, have a listen to the DAC, and given that E1DA is known to be tweaker/DIY-friendly (including making devices like the Cosmos line), let's also talk about what I would consider more "extreme" tweaking for the perfectionist audiophiles!

REVIEW: Sabaj A20d 2022 Version DAC [Part III] - DSD, Headphone Out, AMPT, Subjective Impressions and Summary. (And some more Peru pictures!)

Okay, we're in the final stretch of my measurements/review series on the Sabaj A20d 2022 DAC. This time, let's finish with some measurements around DSD performance, the headphone amp output quality, and let's talk about subjective listening impressions before the final summary on my impressions of the device. (See Part I and Part II for earlier instalments in this review.)

REVIEW: iFi GO Bar - Portable DAC / Headphone Amp (Cirrus Logic DAC, Balanced & Unbalanced).

My friend AudioPhil is really into his headphone gear. Recently he acquired the product above and asked if I might want to play with this for a few days... Sure, this looks interesting!

This is the new iFi GO bar (around US$320), a portable headphone DAC/amp. The USB interface is a USB-C form factor (480Mbps USB2.0 Hi-Speed), and there are outputs for single-ended/unbalanced 3.5mm TRS and balanced 4.4mm pentaconn. Interestingly, the company (iFi, subsidiary of AMR/Abbingdon Music Research) does not specify which DAC chip is used inside. Suspicion is that it's likely the Cirrus Logic CS43198 or CS43131, both are recent chips circa 2017 capable of "pseudo-differential" outputs and low-power consumption <40mW with rated THD+N of -115dB, DR 130dB, maximum PCM 32/384, and DSD256. The specs look good but don't get too excited about these ideal numbers when implemented in a USB dongle.

I don't know what's the point of being so secretive about the DAC chip used (Crutchfield says it's the 43131).