I have nothing to compare it it to. I guess you could go with what people have said about the D1 but with a little bit more s/n.
 
Hopefully I can get a hold of more equipment so I can evaluate both

Review coming soon

There really isn't a whole lot to say. This player will hold a s*!t-load of music and/or movies and/or pictures, but I only use it for music. The hard disk is a little loud at times and it lags somewhat as well, but at 160 gb they couldn't have put solid state drives in yet.

 
First impressions - Upon first opening the box of these (lightly used) cans, the very first thing I noticed how light they were! In all honesty I was freaking out for about an hour, then went to a local used electronics shop where they had the same model a couple weeks back. Apparently they are SUPPOSED TO BE that light, so the relief swept over me. 
 
Sound - I do not have an amp yet, so talking like I know anything would be out of line. Straight lined to a computer the bass is just enough for classical piano. Listening to the album the is in the picture, the experience is amazing. If you close your eyes, you feel like you are sitting in an amphitheater as each composition is being executed. Unfortunately there is fatigue to be dealt with but it isn't so much that it cannot be handled. As others have stated the mids aren't very good, but hopefully that will be fixed with an amp. The word you might have noticed was "executed." A friend told me the K701's suck the life and soul from music. From what I can sense he means, there is a certain coldness to the sound being created. Music isn't as much played as is projected from an instrument
 
Final thoughts - Written reviews are not a strong suit of mine, so hopefully you at least know what I'm trying to say.
 
EDIT - While listening to pre-viking Bathory there is the PERFECT amount of bass! While listening to the Mountain Goats last night I noticed it made John sound even BETTER than normal. I'm still not too hot on these headphones but they are definitely growing on me!
 

This is going to be a short review.
 
-When I took them out of the box they felt like crap, like the smallest amount of pressure would snap the headband in two or more pieces.
 
-Upon first wearing they weren't nearly as tight or sweat inducing as the Skullcandy T.I.'s I had at the time.
 
The sound was nasty. I do not know if this "burn in" thing you people talk about counts with these things or not, but I didn't even want to try.
 
If you can't get them for less than twenty bucks then keep your money.

Okay I'm not going to fill this area with a bunch of BS terms I'm just going to say it straight up.
 
I bought the headphones from a really nice used shop locally, and I was told they were pretty decent. Upon first applying them to the not forehead (because that would be dumb behavior), I noticed the isolation was quite impressive. The guy that worked there was talking but I couldn't hear a damned thing he was saying. The song I tested it with was King Crimson's "Epitaph." The power they gave off was very nice and despite what the assistant said, the bass was of a great level, not too high and not too low. When I got home I listened to American IV by Johnny cash and let me tell you, PURE MAGIC.
 
A couple gripes I had: The fit was pretty tight so I wasn't able to wear them longer than 7-10 minutes at a time, the cord is long as hell so I was sitting in my computer chair holding 75% of it, and the condition they were in was less than stellar. The ear pads were beat to hell, given this means nothing if you buy them new or used from a decent person, but there was no way I would keep the cans and pay $20 for replacement pads. I mean heck at that point I might as well buy them new!
 
I'll will be getting another pair down the line but as of no I can't afford it.
 
These headphones are highly recommended by the community and there is a reason why; If you get these things in new/good condition THEY ARE WORTH EVERY PENNY, and if you get them for a steal of a deal then that just makes them better!
 
EDIT - Now that I have a new pair this can be updated. The music sounds muddy, especially in the mids and highs. I don't know if this goes away after burn-in or not but it isn't that big of a deal.