Bought it with an upgrade caps, cables, and extra tube ,
 
this amp works wonderfully with my HD650, and able to make my earpod sounds wow also hahaa...
the nature of this amp, allows to bring a great potential of gear, even though i never tried any other tube amp, i could say that this amp sounds so natural and quiet energetic i think and doesn't sounds tubey at all,
 
The build quality of this amp is also wonderful, as it was made from pure alumunium with a hairline finishing give a premium finish, even though i believe this amp won't survive if was accidentally drop hehe..
 
a little pic:

 
General Sound Impression:
Got this for about $150 and have this laying around for at least 1 year and 6 month by now, and i only can say that these DAC do sound very nice,
Paired this little guy with a HD650 and i can say that this DAC have some very clear mids, with a nice sound stage and good layering. For me, the only downside from the sound, might be just that the lack of bass impact, but this can be covered by using some amplifier, so the problem is solved,
 
Design Wise:
This Tube modeled DAC, is only about 12 cm long with simple USB input and 1/4 Jack Output, so this could be a very nice transportable DAC, Also this DAC have some quality build, with an almost full alumunium body, make this DAC looks quiet a premium item, it's just this DAC give a lot of heat issue, but this was supposes to be a desktop DAC so this shouldn't be a problem, but this is really worried me sometimes, as a lot of heat might shortened the life span of this item..

gear:
SGS2 with MIUI Rom music player
Go Vibe's Vest
Dacport LX + Objective 2
 
put these iem's into sgs2 and already doing nice
give some portable amplifier/dac, in this case i'm using govibe vest and she's already doing great
put some better amplification and dac, and my ear says that she's a marvelous player

Setup for review
1. Dacport lx
2. Scsag m2m
3. JD's O2

Review

When i put them on for the first time i could really tell that this HP has some nice comfort on it, even though the earpad kinda hard at first..

I start to feel fatigue after 2 hour of listening session, this fatigue feeling is very hard on my left ear, but after 1 weeks of use, this feeling is gradually reduce

As for the sound itself
I don't feel any veiled things like many people said, the vocal is really clear and quiet laidback, allowing each instrument to produce their sound independently.
The next great thing that i feel is the bass that have a nice "grand" feeling, it's feel very differently from my previous HP which is dt880, on dt880 the bass is punch deeply, but doenst have those grand feeling like this HP, the smoothness of it's high frequency also give a nice long session listening with no sibilance (or maybe a little)

As for the sound stage, the dt's allow you hear more deeply, like it was more isolated, but the hd650 is also gave enough staging as you can still feel each location for every instrument