I. PrologueFor those who have followed along on the blog, you may recall that this blog started with some arguments I had with folks on an audiophile forum around the audibility of high bitrate MP3. Back in those days (err... late 2012), there were all kinds of claims made by quite a few hobbyists that they could "easily" differentiate lossless FLAC from 320kbps MP3. I'm sure there are still many in the audiophile forums who hold this view although I think things have softened about the magnitude of differentiability (I think this shift has changed with high-res audio as well).
That disagreement was enough to push me to put out a blind test, to start looking into what I could do to help further my own understanding and awareness around audio hardware. The articles on this blog basically have been the culmination of that pursuit in hopes that the ideas and tests have been useful for others also on this journey looking for some clarity, typically found with more objective analysis.
Objective testing requires disciplined procedures and tools. Methods to reduce variables so that we can have reasonable "apples-to-apples" comparisons and reduce or eliminate psychological biases when we make decisions and search out facts beyond opinions colored by idiosyncratic preferences. Whether it's using an ABX tool, asking a partner/spouse/family/friend/neighbor to change something without our knowledge when listening, or measurement devices - letting the tool demonstrate changes - I believe we can find answers to uncertainties or prove claims. I personally believe objective testing is not only something "nice to have" with reviews, but an essential part of developing insight into the devices being tested and our own perceptual and cognitive limitations.
That's a long intro which brings us to today's preview of a new tool. :-)
When it comes to using an ADC for measurements, over the years, I've gradually upgraded starting with my old Creative E-MU 0404USB from 2012, to the Focusrite Forte in 2016, and now, let's start with a look and listen to the RME ADI-2 Pro FS ADC/DAC. The aim has been that each step brings with it more accuracy for the measurements and this third iteration of the measurement hardware should bring with it opportunities to explore further and continue the process of finding clarity in a hobby that for too long IMO has been filled just with mere opinions - or even worse perpetuation of myths. (Remember, nothing wrong with opinions... But let's make sure it's grounded in objectivity!)
II. A Look at the RME ADI-2 Pro FSThe German company RME has been mentioned a few times over the years on my blog pages. My friend who does studio productions uses this company's professional ADC/DAC devices and provided me with recordings when I was evaluating MQA over the last few years (eg. here, here) done with RME gear. I was impressed with the quality of the recordings he was able to produce. Furthermore, as I discussed with others the idea of upgrading my measurement set-up, the RME name came up a number of times, especially the ADI-2 Pro devices.
This is particularly relevant for my situation because one of the identified uses for the ADI-2 Pro is that of audio measurements (it's discussed in the manual) given the "instrumentation-grade" accuracy of the device. Of interest, ongoing optimizations to the firmware have improved performance in this regard and I see they recently in June added a compensation filter to smooth frequency response measurements. With these developments, it was simply a "no brainer" to get one of these to use for what I do here!
The ADI-2 Pro was first released in April 2016 as a 2 analogue channel in/4 out device with "reference" quality high resolution ADC and DAC while maintaining a reasonable price point (~US$2000 - as usual, shop around for the best price). Check out the detailed review on Sound-on-Sound from 2017. The release of the ADI-2 Pro correlated with the company's 20th anniversary that year.
Earlier this year (April 2018), the "FS" version was released with upgraded clock resolution into the "femtosecond" range for even lower jitter (they call the system "SteadyClock FS") at around the same price point. Remember from a couple weeks ago my thoughts on jitter - practically, I don't believe it's audible but for a professional and measurement device, clock precision is important. Depending on where you are in the world, it should not be difficult to locate a dealer for RME. With the arrival of the FS model, I've noticed a price drop in some places for the "non-FS" model (I've seen ~$1300-1600 on Amazon).
Here's what's in the box:
There's the device itself. Given the capabilities, it was smaller than I had initially expected. Handsome metal construction with silver front and black steel elsewhere. I see they had an all-black Anniversary Edition in the past - that one looked amazing (here's a Russian page with some great internal pictures)!
Inside the plastic bag in the picture are break-out cables for electrical S/PDIF digital input/output (2 coaxial and 2 AES/EBU). There's a small low-ripple external switching power supply and power cable. And finally the manual printed in English and German.
I guess I'm old-fashioned. Even though the manual is online (I see it's a "live" document regularly updated), there's something about a nice manual to thumb through while trying to get things running. It has been awhile since I've seen such a detailed document in hard copy with my purchases.
As someone who has not used an RME device before, there is a bit of a learning curve involved here. Compared to other ADC's I've used - Creative E-MU 0404USB, Tascam UH-7000, Focusrite Forte - it's no exaggeration to say that the features available under the hood with this device is an order of magnitude more powerful! Not surprising when you consider that there's >2 gigaflops of DSP computing power working along side the FPGA (Xilinx Spartan-6) handling much of the executive duties. As such, sections in the manual are devoted to describe the various modes of operation ("Basic Modes" like AD/DA, USB, Preamp, Digital Thru, straight forward DAC), metering, DSD in/out, DSP features (5-band parametric EQ, SRC, headphone crossfeed, tonal adjustment), RME's DIGICheck digital stream analysis, and in/out modes like 4 analogue channel playback (USB multi-channel mode compatible, can go up to 6/8 channels if one uses the digital outs). The system is capable of handling the plethora of sample rates all the way to PCM 768kHz and DSD256 for playback and recording (I have yet to try DSD recording presently). Another impressive feature with this device is the dual headphone outputs which are actually sourced from 2 separate DACs; "PH 1/2" uses the same DAC as the main XLR/TS output in the rear while "PH 3/4" uses a separate converter allowing independent settings like volume and parametric EQ for each output (great for A/B testing headphones or for EQ compensation tweaking). Furthermore, each headphone amplifier is capable of high current output even into low impedance transducers (0.1-ohm output impedance, spec'ed at up to 1.5W into 32-ohms with minimal THD). Oh, yeah... Did I mention that you could also use "Balanced Phones Mode" - each headphone output to a single channel, increasing the power to 2.9W/ch? (Remember, for consumers, this is like the Pono balanced headphone mode.)
If the above summary paragraph sounds overwhelming, I'm sure you're not alone in feeling this way :-). While getting the machine running can be done quickly and far from rocket science, there is a huge amount that this thing can do. Going through the manual, I get a distinct impression that the folks at RME are tech geeks looking to wrestle every bit of capacity from the professional-grade hardware. As a professional device, the documentation holds nothing back in attention to detail with specifications, an array of measurements, latency discussions, consideration of CPU utilization and jitter. Recently, they have put work into intersample overload awareness with the metering and providing overhead when performing sample rate conversion. You'll see this level of technical engagement on their User Forum as well.
III. A Time to Listen!
IV. Preliminary Impressions...
|RME ADI-2 Pro FS: USB Audio Class 2.0 mode under Windows 10 without drivers installed, all sample rates to 32/384kHz available under the Windows Driver Model (WDM) Audio Support.|
I think that's enough for this week!
Until next time, enjoy the music :-).