I'm not an experienced audiophile, so i'll make it short.
The PS500 is really easy to drive, you can plug it into your ipod with an adapter and it'll still sound audiophile level, but an amp does help.
Design : As shiny and good as the picture might look, these headphones, IMO, look pretty ugly, I won't consider that much of a problem since I usually only use open headphones at home.
Comfort : Not too bad, the clamp is not too strong and it stays on my head quite well. The headband seem to squeeze my glasses a bit, could get annoying at times.
Sound : These headphones are quite source-forgiving, but they are not that music track forgiving. Make sure you are listening to a good live recording or a nice balanced mix. If you are doing so, even a mp3 file sound quite nice.
Treble: The treble is fast and FORWARD! It is slightly bright but really fun.
Mids: The mids are once again, exciting and forward. The male vocals seem to shine a bit more than female vocals do on these headphones. The lower mids and upper bass is where this headphone really shine. The bass guitar is fast and really clear. The drums in general sound amazing, you could feel the physical thump coming from the drums and since these headphones are quick, the cymbals also sound very clear.
Bass: I'm not really into too much bass since I don'y listen to genres with really strong bass, but I tried some Dubstep and Nightcore mixes on iTunes and Youtube . I noticed that the bass is really strong but decays slightly too tight and fast.
Conclusion: These headphones are Really forward, slightly bright and really exciting. I would suggest these for the following genres:
1.Rock
2.Rock
3.Rock
Well... It also depends on which genre of rock you listen to. Since I mostly listen to Metal and faster rock, I think these are the best. The LCD2 and HE500 may do a bit better with slower rock.
Hope the short review helps.
Also, I thought the treble was slightly unimpressive, moreso than the mids. Both are easily fixed though with a small bump at 1k and a slightly larger bump starting at around 8k and going up from there