I don't like writing reviews, but I said I would do so for the UltraDAC ("UDAC"), so here goes. However, before doing so, a few words of disclosure. I like HeadRoom and have been a customer for a few years. I know and consider Tyll a friend (while also knowing full well that Tyll has legions of friends here (i.e., I'm not special)). I don't believe that gear will sound much different at hour 1, 500, 5000. And I don't care at all about cables. I let you know this not because I dispute the premise about such things, but rather to let you know how I approach gear and how I hear things. Therefore, what follows with respect to sonic impressions is based upon listening sessions aggregated over time with an assortment of random cables.
I bought the UDAC and returned it within the 30-day window. First, a big thanks to HeadRoom for its awesome, no questions asked return policy. The smooth transaction both purchasing and returning the DAC is one of the reasons why I will keep going back to HeadRoom.
As you can see, I am a HeadRoom fan. I've owned a Bithead, MicroStack (older version), Desktop Balanced Amp with DAC (home versions), DPS, and the UDAC. My favorite of the aforementioned was the Balanced Desktop. I still miss it. My least favorite was the Bithead. As for the UDAC, I liked it, but didn't love it, which is why I returned it.
Build Quality
The UDAC is a well-built and straightforward device. If you like HR's desktop aesthetic, then you'll like this. If I have one complaint about the build, it's that I think it would benefit from some more mass. Not sure how HR would accomplish this, but the UDAC was light enough that it moved around pretty easily. Of course, I also have a 55 pound DAC, which is a bit overkill.
Note that the UDAC does not seem fragile or delicate. I just wished for some more heft so that it didn't have as much play when disconnecting cables, etc.
Operation
The UDAC is not a complicated device. The front panel has the power toggle switch, sample rate indicators, input selection button and indicators, and filter selector and indicators (the filters made little to no difference to me). The selectors are soft touch buttons, which are a nice update from HR's toggle switches. The display is easy to read. I would have liked a "dim" option for the bright green LEDs. I also would have liked it if the UDAC remembered my input settings after power cycling.
The back of the UDAC has coax, optical, and USB inputs and unbalanced and balanced outputs. All solidly built and easy to use.
Sound
As noted (correctly) by Icarium above, the UDAC uses the ES9008 Sabre chip. I've heard a bunch of DACs, but none that use the Sabre. Unfortunately, I've been swapping in and out a lot of gear lately, but I believe most of these impressions are based on the UDAC feeding a KGSS DX to my O2 mk1 and a GLite to my HD800.
One of the first things I noticed about the UDAC was how dead quiet it is. This DAC builds on and greatly improves HR's already good "black between the notes" performance with its DACs. The black background lends a sense of air and space to the instruments, which, in turn, adds to a nice soundstage. This dead quiet combined with a non-lingering decay make for a sound that is very quick and agile.
Quick/agile DACs are sometimes associated with brightness. Such is not the case here. I found the UDAC to be right down the middle. Not bright, not warm. Rather, the UDAC sounded smooth and laid back to me. To a fault. Despite the UDAC's sense of speed, air, and space, my perception was that it lacked the midrange attack that gets my toes tapping. I find female vocals to be a good test for whether I love a DAC. The UDAC handles female vocals very competently, but they did not leap out at me in the way that some other DACs do, which disappointed me. I am not sure that this is an actual flaw in the UDAC, it very well be that I prefer a sweetened midrange, which is actually a way for some DAC designers to get away with less technically savvy designs. Or I could just be hearing things.
For example, with rock, I find the Electrocompaniet ECD-1 to be a very satisying sounding DAC, which I attribute to its midbass and slightly forward mids. However, I sense a bit of congestion, too, with the ECD-1, which sacrifices detail and slows down the presentation. This congestion could be a deal-breaker for some. And the UDAC does not suffer from the same flaw. Rather, it presents the detail, but not in a splashy or tizzy way like the Benchmark DAC1. At the same time, the UDAC lacks that punch in the middle that I find satisfying, especially with vocals and guitar.
Things change a bit with classical. With the ECD-1, the midrange can sound a bit artificial to me with classical music. Here, the UDAC again plays it straight, though laid back. For a classical lover, I think the UDAC would be a solid choice. For a rock lover, I'm not quite so sure. And, sorry, I know almost nothing about jazz so no opinions there.
Of the DACs I have heard, I think that the UDAC sounds most like the North Star m192 mk2. The NS beats out the UDAC in terms of soundstage and musicality. I think the UDAC wins on detail.
Bottom Line
The UDAC is what you would expect from HeadRoom: solid, capable, and satisfying. However, the UDAC is not for everyone, like all gear. If you are like me, and want a DAC that sweeps you up in the mids, then I suspect that the UDAC isn't for you. However, if you prefer a DAC that favors coherence above all else, making sure that each constituent part is represented equally, then the UDAC is worthy of your consideration. I will note, however, that the UDAC is competing with a bunch of highly competent and entertaining used DACs at its price point.
HeadRoom's UDAC is a well thought out piece of gear. And while it was not quite my perfect cup of tea, I also would not have shed tears if someone said I had to keep it, as the UDAC is quite capable of delivering a musically satisfying experience.
