First thing you'll notice is a very elegant design, brushed aluminum and nice LEDs for it's input/output displays. The unit has amazing build quality for something of this price, it's got some weight to it and the USB connector fits very snug and the unit has nice tolerances all around. Top volume knob is very large and gives you very fine control.  Headphone output isn't the loudest or most powerful, for harder to drive cans I recommend using the fixed volume outputs 3/4 using TRS to RCA adapters to connect to external headphone amplifier like a Magni or O2. 
 
I needed a small interface for using my Yamaha HS8 monitors and connecting my Shure SM7B mic.  I've used a few budget interfaces, the Focusrite 2i2 and the Audiobox USB both ended up failing, the Audiobox was awful.  I really recommend spending the extra money for this one if you are looking for a nice interface under $250. 
 
The microphone input is a little quiet for the Shure SM7B (which is a very demanding mic) so if you are using a dynamic mic I'd recommend getting a Cloudlifter or Fethead to give them a little boost by using phantom power.  I haven't tested with a condenser mic but I'm sure it's much more usable with one of those if you are going for a cheaper solution.  It has MIDI support so you can feed a keyboard into it. 
 
Also includes 4 TRS inputs, 2 of those being XLR/TRS combo inputs.  Also has Digital Coax I/O which could be useful for connecting other devices, personally I haven't really used them and would of preferred Optical SP/DIF but that's just me.  Overall I'm impressed with the quality for the price and would recommend this unit.

Be aware you can't listen to inputs 3/4 (the back TRS inputs) in realtime but you can use the headphone output to listen to inputs 1/2 (the XLR/TRS combo with volume controls) in real-time, which is great if you want to hear your mic through your headphones or speakers, as inputs 1/2 can be monitored on outputs 1/2 or 3/4 which you can use the headphone selector to choose which output to hear.

It's transparent to my ears, I'm not really sensitive to hearing if a DAC is "good" or "bad" but that's up for you to decide.  I would of liked XLR outputs as those connectors are much sturdier but it would make the unit larger and more expensive.

I was sort of ignoring of Grados thinking they'd just be your typical treble blaster with non-existant bass and the build quality sort of threw me off.  But at $79 I said what the heck, I need to try some Grados and then I could at least say I have tried them and didn't like them.  I was pretty wrong, I got Ear Zonk Red Pads, I'm a sucker for making things look different (I sort of hate having the same look as everyone else)  And I heard they change the sound ever so slightly even being a similar flat on ear pad and this would be my guinea pig for any pad mods (I did the coin mod on them and I put a black eyeglass cleaner over the driver (I don't want to see the driver so exposed.)

Anyway, I put them on and tested a few songs, when fast choruses kicked in the felt like they delivered a completely different sound.  I had been to used to more easy listening headphones and more neutral cans.  The pads of course sort of reminded me of days wearing the headphones that came with my CD Walkman.  But they were surprisingly comfortable for some time.  Then all of a sudden it's just like what did I do to my ears, they have a bit of clamp (I'll be sure to stretch the headband.  with the flat pads it seems easier to position them correctly than with some large over ear cans which I get OCD because one side will be more foward, lower etc and change the sound.  These I can get a nice perfect fit, I like the sliders for the earcups, my LCD-2s get annoying when the notches drop a whole level if I shift the headphones slightly.

More on the sound: good bass, not basshead bass, SOME kick drums can sound a little like 909s when they are real sets.  A lot of the time drums will really stand out with nicely done cymbal crashes, snare hits and the lot.  Electric guitars really shine through, on my other headphones I paid less attention to guitars they felt almost more like background sounds.  The soundstage on these is only so good, I heard different pads would make it a little better.  The majority of my headphones have decently wide soundstages and are very comfortable.  This guy is sort of the odd one out.  I really wish these were somehow closed back cans, I picture these as a can people should be walking around town in, or riding a skateboard hanging on to the back of cars (sorry had to throw a favorite movie reference in) I think these are going to have me enjoying rock music more.  I stopped listening to as much rock with my higher priced cans, even bands like Marilyn Manson (yeah I know most of you probably hate him) with his trio of great albums sounded too laid back with others but these cans brought them back to life.  Idk but it seemed liked songs had a wider dynamic range with these, that could just be my mind playing tricks.  The Earzonk S-Cushions (before quarter modded) seemed to make some parts a bit smoother and rounded out while making little treble peaks stand out more.

So overall if you want a cheap headphone, aren't going to be wearing them very long periods more than 2 hours.  I think these will do quite nicely, I have good regard for regards to Grado's sound quality, and being able to change the sound so easily with cheap pads is very nice.  Psh I can't remember when pads have ever been less than $15.  They have a perfect length cable for listening with a desktop DAC/AMP  I've been switching between my Magni (Sys lowering volume to give me more channel balance with the pot of the Magni wish needs to be at past 10 o'clock to have good balance IMO) which is connected to my Dragonfly 1.2 and Loki.  I also switch to my Dragonfly directly, and probably one of the better options at my disposal is using the FiiO X3 as a DAC for my PC music collection (128GB can only store so much)  These are a can which I'd easily $40 more after listening to...but don't do it Grado, I want more money for pads haha.

If it wasn't for the comfort and lack of soundstage I'd give it a higher rating.  If this was a closed can an it sounded like that, we'd have a really great portable, a lot of people might buy this thinking it's a portable and end up angering a lot of people near them, haha.  I can like Sennheiser's and Grados.  Don't see that too often

For some reason these reminded me of my DT990s when I put them on in terms of sound signature, not as sparkly treble (which is sorta sibilant on the DT990s) with a nice low end.  Mids are a tad recessed I wouldn't say it really takes away from it though.  The earpads seem like a perfect size and fit.  Originally I didn't like the style, but it grew on me much like how the HD598s, and HD650 looked strange to me at first.  Definitely the only headphone I really liked out of the B&W line-up, I just have not tried their C5.  Got myself these as a new years present, I needed a closed back around ear headphone and I tried them out at work.  I was sort of turned off to their headphones when I first tried the P5s we had out laying around (They don''t say P7 on them, but since they all look so similar I thought it was the P7 so I thought..."This is their flagship headphones?"  Then later on I saw a picture of the P7s...and I saw the P7s weren't on-ear they were around ear...dumb me.  So I went to one of the B&W displays and behold the P7 hiding.  Plugged in my X3 tried them out during slow times and my lunch.  Ended up buying them for a good price (I won't list it here) and am very happy with them.  The soundstage was pretty good for a tiny little headphone.  I did wish companies would stop making proprietary replacement cables, but at least the cable is replaceable, I also would of liked a 90 degree angle jack 45 degree, or even better the momentum's rotating connector.  Overall I really like these headphones, I've only had 3 days of owning them but definitely a great buy.

So I got these real cheap, I thought what the heck for $15 I can't go wrong.....I was wrong.  Well they are listenable, I hardly call them a gaming headphone besides the mic built in, explosions were pretty fun in Battlefield.  I didn't have a good mic at the time so it was a godsend to have one to talk to my friends on teamspeak, mic quality is just okay even with a soundcard.  Honestly I probably would sell them if the shipping didn't cost me more than the headphones, maybe I'll give em to a friend if their mic/headset breaks.

Overall a great little card. Dolby headphone is amazing I preferred this card to my Sound Blaster Z, I sold that card when I needed a bit of money and bought this one to replace it for cheap and I actually liked the sound on this one more for gaming.  It has a decent amp built in but if you want to plug another in for using dolby headphone it does not have a standard line out option, so I recommend using the optical out to send to something like a FiiO D3 and then connecting your amp to avoid double amping.  It is great that dolby headphone is sent through the optical.  It does lack Dolby Digital Live so sadly you aren't going to be able to send out surround via optical, you have to use analog connections to computer speakers for that.  For the price though it is a splendid card, the microphone input is clean and gave me less noise than my Sound Blaster Z/
 
A weird thing about the card; it fit into my first PC case just fine but when I upgraded to a Nanoxia Deep Silence 1 case (This case is nice and quiet!) The DGX did not fit properly in the PCI-E slot.  I had to bend the backplate to get it to screw in to the case and it still sticks out.

I love the sound quality, one of my first good pairs of headphones for music.
Soundstage is very lacking, don't even try to play a game with it (Could pinpoint enemy footsteps better with a mono speaker haha)
 
The folding is sort of nice, but annoying at the same time.  I let my friends try them on and they always manage to flip the earcups the wrong way and get confused.
 
Sometimes the highs are overbearing.  My ears tend to be hurt by some youtube videos and some music.

Alright well I just recently purchased it, installed from CD fine on Windows 8 64bit, not so much on Windows 7 64 bit had to find a strange hidden zip file to get it to work.
 
This thing is ridiculously loud, could be good for some high impedance headphones.  Turn it down all the way before you plug in your headphones.  I can hear pretty loud sounds when the system volume is set all the way to 0 (doesn't give me much range for small volume increments.
 
The SPDIF works great with it's provided 'mini toslink' connector.
 
The USB extension cable it comes with is quite nice as well.
 
I have yet to use the microphone input nor the virtual 7.1 for headphones (ATH-M50 isn't good for that)