So far from these headphones I can notice a very large and great soundstage and instrument seperaration. Complex and well recorded drumming sounds very tight and dynamic. The bass is probably the only low point on these, but it doesnt affect anything in my case cause I like music to sound like it was intended to. These aren't rock cans if I can tell, and from what Ive read they don't quite do what the beyers and grados can do concerning rock, and I can easily understand why. Female vocals and jazz and any sort of ambient and post-rock with sound very fine on these, as the details and the airyness are a very strong point.

The A-T AD900s are a wonderful headphone, especially for the price of ~$230. The lows are very detailed and not boomy at all, however, it doesn't extend terribly deep, though more than many, and the impact is pretty good. Mids are smooth yet detailed, and there aren't any dips or peaks. Highs are exceptional, with no audible drop as the frequency extends to the top. No sibilance is present and cymbals sound very realistic. The entire sound has a good "snap" to it, especially snare drum hits where it almost seems like you can feel it. These headphones are not tiresome at all even over extended listening periods.

Soundstage is fairly wide, and you can hear positions of instruments easily. Amplification doesn't do much for these, and they sound good out of pretty much any source that isn't junk. These headphones are VERY comfortable, with the wing system giving as little pressure as possible on your scalp while the large velour earpads press softly against your head. They also seem pretty durable, with a hard metal mesh covering the outside of the drivers. They are very light, however.

Overall, these headphones are excellent, and it would seem hard to find a more detailed, non-fatiguing headphone at this price, or more.