Pros: Lots of inputs (COAX, USB, Optical), AC powered! Amazing with the HD-650/Q701
Cons: none yet
This is a really tough review because to my ears this DAC doesn't really have it's own signature. So the best I can do is compare it to my old ODAC and Modi, but all based on memory.
First off, Headroom had stopped selling their own brand of gear so I just HAD to buy this. Headroom should reconsider and hire a marketing guru. The small size and plain design doesn't help much. They're built like a tank though and not made out of plastic! Their stuff is much better than all the other Schiit. I skipped it for over a year because I thought it'd just be a side-grade to what I already had. WRONG! Since the Headroom Micro Amp + Astrodyne is the best solid state amp ever made under $500, I had to buy it to complete my "Micro Stack". The Headroom Micro Amp + Astrodyne is so neutral IMO that if you don't like it, maybe you like more coloration (nothing wrong with this) or it's due to the DAC or stock power supply. To me it's like a slightly re-tuned O2 on steroids with all the rough edges taken off. It can drive almost everything, but maybe sweat a little with the He-6. It has 1.21 Jigawatts into 32ohm. OK, it's more like several watts.
On the first few days it was not like a night and day difference. I found that some songs sounded basically the same.
After maybe 3 months I can say that the Micro DAC is dead neutral, but yet very very revealing of recording bit-rate and quality. Much more so than the ODAC and Modi. On the Modi you feel as if it's a much more smoother and forgiving DAC. Harsh tracks are not as bad and they're easier on the ears with the Modi. I was pretty shocked when I first used the T90 with my Micro Stack and first heard this when I switched to the Modi. The Modi + Micro Amp despite being not as revealing, was actually a nice and musical combo, but holding the T90 back a little (when it comes to how revealing the T90 can be).
With the Micro DAC + Micro Amp using both with Astroydyne power supplies, the soundstage of the HD-650 is as large as i've ever heard it. On some more expensive amps the sound can often be warmer and more closed in and congested. The HD-650 with this setup and the right recording can be very very wide open, airy and spacious sounding. You can hear this easily with "The Buena Vista Social" club. You feel as if the instruments are coming at you from all around, up on top of your head and even slightly behind you. All the instruments are very full sounding, as if you can FEEL them. They have much less body on the ODAC and Modi perhaps.
In comparison the Modi's sound is slightly more "hazy" sounding. Harder to hear in between things. Still very clear, but less expansive and less airy. Ultra subtle details are harder to hear. You can actually HEAR the clearness of a recording properly with the Micro DAC and on the Modi/ODAC this is a little harder. Some recordings actually can sound more muffled on the Micro DAC, but only due to the recording.
When you listen for hours with the Micro DAC you can easily say to yourself "That's probably a 192kps mp3 file" or something like that and you're almost always right. OK, I can't tell the exact bit-rate but it's usually just a low bit-rate. I know there are plenty of lossless files that still sound like garbage due to recording.
When I bought this I had my usual expectations. I thought it would probably be bright or thin and harsh. No, it's not. It's just very clear/clean and only reveals what's on the recording. Despite being basically dead neutral, it might actually be a touch warmer than the Modi. It's not actually warm itself, but possibly compared to the Modi.
It never sounds thin/harsh or bright unless it's the recordings fault or the headphone.
I actually think the Micro Amp + Micro DAC is so good that the Q701 and HD-650 hold it back. To me they're definitely mid-fi, but I would glady use them with an HD-800/T1 or LCD2.
The cost of each unit when new was around $350 (+$60-90 for the Astrodyne PS), but to me they're worth up to $600.
As a whole, the Micro DAC is very clean/clear and sort of analytical. Not thin or bright, but just extremely revealing. If you like your DAC to ADD warmth, don't bother with this one.
This uses the Cirrus Logic CS4398 DAC chipset and so far I love it! My Ipod Touch 2G uses a Cirrus Logic DAC, but this definitely sounds much more refined and less bright/thin.
BTW I'd love to compare this against the Bifrost. I'm pretty sure it would be a side-grade. I'd love to get a review unit, but probably not going to happen. I bet the Bifrost also is like a slightly more revealing Modi, but way better. I'm a huge fanboy of the Modi but the Micro DAC is definitely an upgrade.
NOTE: I will update this review the more I listen to the Micro DAC. It's replaced the Modi, but I've kept the Modi since it's still a keeper.