MEASUREMENTS: RME ADI-2 Pro FS R Black Edition as DAC.

 

Well friends, it's time to publish some measurements of my new RME ADI-2 Pro FS R Black Edition ("FS R BE") unit as DAC. For background, refer to the Preview from August and a couple weeks back, I had published results discussing the ADC function.

As you might be aware, since 2018, I've been using the older RME ADI-2 Pro FS ("Pro FS") for ADC and DAC duties in my measurements. It has performed like a champ and in fact, given that the ADC function is almost identical between the two units, there's certainly no reason to retire the "Pro FS" from measurement duties.

What we know is that as a DAC, the "FS R BE" should perform better than the "Pro FS" due to the fact that the internal AKM chip has been upgraded to the AK4493 from the previous AK4490. On paper, this represents a +5dB improvement in SNR and +1dB improvement in THD+N so we're not looking at Earth-shattering differences in specs numbers. Let's see if we're able to measure these differences on the test bench and identify any other changes to the DAC's performance along the way...

MEASUREMENTS: RME ADI-2 Pro FS R Black Edition as ADC.

About a month ago, I posted this preview of the RME ADI-2 Pro FS R Black Edition AD/DA converter. It has been a wonderful month of simply listening to this device without a care around performing measurements. For listening, I have it set up as per the image in my sound room with the Raspberry Pi "Touch" running RoPieee previously discussed.

So far, from a subjective perspective, it has been a joy to listen to music with this machine.

Alas, as a "more objective" audiophile, it came time to have a look at the performance for this device to check if I'm missing any significant limitations. Over the years, I've discussed limitations to human hearing as well as the idea that many of our audio electronics these days have surpassed human auditory perception such that while measurements of DACs or amplifiers can show limitations, often these are beyond the resolution thresholds of human hearing/perception. Remember that while not all measurable anomalies need to be chased after when the goal is simply to be able to enjoy music, technical "ideals" are useful for devices one may want to use as a "reference".

So to start, today let's just focus on the ADC side of this RME device. Remember that the RME ADI-2 Pro FS R Black Edition (again, let me just call it the "FS R BE" for short) is an evolutionary step from the ADI-2 Pro FS ("Pro FS") that I started using 2 years ago. Consider this article as building on some of what we already know about the Pro FS as an ADC from 2018 with requisite repeated tests comparing the two machines and using today's software.

PREVIEW: RME ADI-2 Pro FS R Black Edition AD/DA Converter

Look what showed up at my door (finally!) the other day. This is the latest hardware update to the RME ADI-2 Pro line of converters, the RME ADI-2 Pro FS R "Black Edition" - quite the mouthful! Let's just use "FS R BE" for the rest of this article for short in reference to the name.

Currently, the street price is around US$2,000.

Back in mid January, RME debuted this latest iteration of the ADI-2 Pro at NAMM 2020. Since 2018, I have been in contact with Matthias Carstens (co-founder of RME) off and on about the ADI-2 Pro FS that I have been using for measurements on this blog. Shortly after NAMM, I contacted Matthias about getting an upgrade as I could use two of these ADI-2 Pro devices - one for the soundroom and another for my test bench - when the company starts shipping these.

MEASUREMENTS: RME ADI-2 Pro FS as DAC (Part II - frequency response, noise, distortion and jitter)

As we saw previously, the RME ADI-2 Pro FS is based on the AKM AK4490 DAC chip and provides a good assortment of features like filter settings. We've seen that the headphone output amplifier provides plenty of power and the beginnings of what looks like a highly accurate DAC; consistent with my subjective opinion.

Time for part 2 of the objective evaluation today as we continue to explore the DAC output quality.

MEASUREMENTS: RME ADI-2 Pro FS as DAC (Part I - output levels & digital filter settings)

After having explored a couple weeks back the ADC capabilities of the RME ADI-2 Pro FS, for this installment, let's start with evaluating the DAC output quality of the device and in the process examine the objective fidelity with audio playback.

Remember, with that previous article, I had already discussed my subjective opinions based on listening sessions. My opinion has not changed in the last number of weeks as I'm still very much enjoying the sound I hear hooked up to my main system. Subjectively, the output sounds very clean, has a neutral tonality and low noise level very much like the Oppo UDP-205 and other high quality DACs. As usual, it will be interesting to compare measured results among the different devices I put through the test bench.

But before we do that... Let's start with the basics and some of the "microscopic" measurements I usually begin with - things like output levels, filter settings, etc...

MEASUREMENTS: RME ADI-2 Pro FS ADC performance and as measurement hardware.

I discussed the features and some listening impressions of the RME ADI-2 Pro FS ADC/DAC a couple weeks ago. As I noted at that time, my main aim in owning this device is for the purpose of using it as an ADC for measurements here on the blog going forward.

For the purpose of measurements, we want a tool that can allow us to obtain reproducible results and good accuracy. Over the years, I've achieved reproducible results with consistently minimal inter-test variation by standardizing the way I run most measurements with the digital sources, cables, standard procedures, and types of tests I run. What I want is better accuracy - an ADC that has lower noise floor for improved resolution, doesn't add as much of its own distortions, have higher timing accuracy (eg. for jitter tests), and perhaps more features to expand the measurement quality (eg. higher sample rate to capture impulse responses more accurately, and can handle wider input levels for the range of devices tested).

Given that this is the priority, instead of measurements of DAC performance first, let's get straight to describing the characteristics of and using the ADI-2 Pro as a measurement tool which means we'll need to get a taste of how well the analogue-to-digital capability performs. Let's compare the results I'm getting from the RME to my previous measurement ADC device over the last couple years, the Focusrite Forte for a sense of the changes in resolution I can expect from the new upgrade.

PREVIEW: RME ADI-2 Pro FS AD/DA Converter

I. Prologue

For 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!)