Pros:
- One of if not the most feature rich DACs on the market
- Very Compact
- Excellent reference sound, both subjectively and objectively
- Decent inbuilt headphone amp, and absolutely stellar IEM port
Cons:
- Headphone amp is somewhat cold
- Reference tuning might not be to everyone's tastes.
Review:
I've owned the ADI-2 DAC for a couple years now, and figured I should write a review
Initially I bought it primarily so that I could add EQ to my HD800S headphones, whilst still utilising ASIO/WASAPI Exclusive outputs of various players.
And since then, despite having tried a large number of other dacs, it stayed as my main source for a handful of reasons.
Design:
The design of this dac is compact, sleek, modern, and unobtrusive. It stacks really well with devices such as the THX AAA 789, and its design has clearly been well thought through.
Even simple things like the glowing ring around the volume knob make it incredibly easy and a joy to use. It is in my opinion a nice looking device, without standing out too much. Thereby allowing it to fit in with a wide range of setups. My only small gripe is that the position of the two smaller encoders and how they are used to navigate the menu is a tad awkward at first, but fine once you have gotten used to it.
Other than that there is not too much to say.
Features:
This in my opinion should be the main reason to purchase this DAC. It is by far the most feature rich dac I have ever used, with far more features than you would even find in the majority of full-fat media players on a computer.
The DSP volume control on this dac is excellent. Full 32 bit with dithering, in conjunction with the hardware reference level adjustment means that the volume control on this dac is quite likely going to be superior quality to all but the most excellent preamps. I found that I actually had better results by controlling the volume with this dac, and leaving the pot on my amps at max, as the volume control of the ADI-2 was superior to the pots.
The other killer feature is of course, EQ, and not just EQ, but dual EQ, meaning you can have separate EQ curves for the left and right channels, thus allowing for room correction, headphone driver imbalance correction, and even correction of asymmetrical hearing.
It also allows for various levels of crossfeed, channel balance, and selection of different digital filters.
The long and short of it is, just about any DSP feature you could possibly ask for in a two channel system can be done directly on this DAC.
Sound:
Of course, the most important aspect of any DAC, how does it sound?
In the case of the ADI-2, it sounds good, very good, with some strings attached. If you are one of the people that believes all dacs that measure well sound the same, i'd suggest you skip this part. The ADI-2 measures excellently and that should be enough.
If however you have ever tried multiple dacs and/or are aware that dacs do not all sound alike, despite what the SINAD chart says, then you will probably be more interested in this.
The ADI-2 is an exceptionally clean, resolving and uncoloured DAC. It is however most certainly taking influence from RME's professional level gear, and giving a reference sound signature. One that will absolutely highlight any flaws in mixes and present music in such a way that it is both incredibly enjoyable, but also quite obvious when something has not been recorded or mastered well.
Out of the box, on the stock "SD Sharp" filter, the ADI-2 dac sounds good, but to my ears somewhat flat and "matter-of-fact". The easiest way to describe it would be to say that it sounds like the HD800 of dacs.
However, change it to the "Slow" filter, and music starts to feel much more alive. Transients are still exceptionally well presented, but the overall signature is a tad less cold and clinical.
If you want to truly make the ADI-2 shine, I would STRONGLY suggest trying some external high quality upsampling, with programs such as HQPlayer.
The inbuilt digital filters are often the weak point of many D/S dacs due to the limited computing power available, and the ADI-2 is no exception. The inbuilt filters are not bad by any means, but using sinc-XTR-mp or sinc-ext2 through HQPlayer led to a much better result. The soundstage opened up, timbre of both vocals and instruments were improved, and it really felt as though the DAC could show off what it could do without being held back by having to use mediocre quality filters for the sake of efficiency.
The high quality sound does not diminish in the slightest when using volume control. The ADI-2 by default will adjust its output reference level such that the minimum amount of DSP is used, but even using DSP alone, the ADI-2 handles low level operation exceedingly well, and so if you are using an ADI-2, there is no need for a preamp or external volume control at all, unless of course you are wanting the preamp for flavouring or output/input selection reasons.
The DAC also does native DSD. And when playing the same song, comparing both native DSD, native PCM, as well as upsampled PCM and DSD, the common descriptors were that DSD sounded more "natural" and enjoyable, but lacked some of the lowend punch and overall attack that PCM displayed.
Internal DSD to PCM conversion was to my ears of poorer quality than any other option and i'd recommend avoiding it.
The ADI-2 does not to my ears sound as "enjoyable" as some less professional oriented products, such as those from chord, or R2R dacs like the holo spring and denafrips ares. But its technical performance, and the ability to tune and customise your sound with its vast array of features could well mean that after some tweaking, the ADI-2 will suit you better than most other options.
In terms of raw sound quality alone, I believe you could get the same quality cheaper, or better quality for the same price, but without any of the wonderful features. However those features are absolutely worth paying for.
The headphone amp:
The headphone amp in the ADI-2 is very much a nice addition, and seems to perform about as well as a budget option such as the JDS atom. It has plenty of power, able to drive even more power hungry headphones like the Hifiman Arya and HD800 with no issues at all. However don't expect to be running HE6/susvara.
The headphone amp sounds quite cold and clinical to me. And this is most definitely the amp itself. Even connecting the dac to something like the THX AAA 789, which is known to be a very "clinical" amp, the inbuilt amplifier sounds quite lean in comparison.
Its great to have, but for a dac of this quality, do it some justice and get a decent separate amp.
The IEM port however is a different beast. Unfortunately I do not have too many IEMs, though my personal favourite, the moondrop blessings, sound better through the IEM output port than just about anything else I have tried. It is incredibly clean, musical, and is NOT in any way just a tacked on output port.
Internally it is separate from both the main headphones output, and the rear outputs, so clearly RME put some work into this, and it shows.
Conclusion:
The RME ADI-2 is an incredibly feature rich DAC that provides an excellent reference sound, in a small package, for a fair price.
In terms of pure musical enjoyment some other options may surpass it, but it remained as my main DAC due to being unquestionably brilliant in so many ways. Others may sing better, but I can make the ADI-2 sing in any way I like.
With external upsampling the sound quality is vastly improved.
My ADI-2 is being replaced by a Holo May (and any needed DSP will be done in Roon), with which in terms of sound quality the ADI-2 simply cannot compete (though given their pricepoints it would be unfair to expect a fair fight.) But I will absolutely miss the ADI-2 and strongly recommend it without any hesitation.
