The bass on these headphones is wonderful when given the right amount of power and boost. The lowest end isn't very powerful or impactful, and one might miss the super-low slam of some more bass-heavy 'phones. However, it is present, and the mid-low bass (35-80Hz) is extraordinary. This part of the frequency spectrum is produced with an extremely punchy, tight, and fast sound. While you won't get the rumble and weight of the lowest bass, I think the quickness and accuracy of the middle-low bass makes up for it. Overall, I'd say two thumbs up.
The AD series of the Audio-Technica lineup is well regarded as having some of the finest sounding midrange for the price. I agree 100%. Vocals are produced very accurately and have a "dry" sound, where everything can be clearly heard without being too harsh or up-front. All the detail is present while not overbearing, which is great for me, as I can't stand metallic-sounding voices. Guitars are also reproduced well, and riffs in metal/hard rock songs are very intense and dynamic. I'd say if you like power metal or any type of harder, faster rock, these headphones should be high on your list to try out.
Again, detail in the high frequencies is excellent. One thing I noticed as being very apparent compared to other headphones (and speakers) is that the clicking on the strums of guitar strings is audible and clear. I think it adds to the clarity of the overall sound of especially acoustic music. Cymbals have just the right amount of sizzle without being overly sibilant or metallic, which was a pleasant surprise to me. Overall, the high end extends to inaudibility, and is not peaky or rough sounding whatsoever. The one complaint I do have is that the entire treble range seems to be elevated in comparison to the rest of the spectrum, especially the bass. However, this isn't a problem to me, and isn't fatiguing unless I listen at high volumes, which I rarely do.
One thing I also have to mention is the "snappiness" these headphones have. Noticed most on snare drum hits, it's almost like I can feel the hit of the stick on the drum head. It literally makes me flinch when I have the volume turned up, and it really adds to the live sound I think these 'phones have. I doubt anyone could call these headphones slow or bloated, because to me, it's exactly the opposite.
The velour pads on the earcups is very pleasant to have on your ears for very long periods of time. There is no clamping force, only enough to keep them on your head. The self-adjusting wings on the top replace the traditional headband, which means less pressure on your head as well as less material touching your head. I never felt my ears get hot like many closed-back headphones sometimes made them, and overall I found them to be very comfortable for many hours.
The cable design is single-ended, with the cord going into the left earcup. The cable covering seems to be made of a rubberized material, and is relatively thick for a headphone cord. This ensures that there is minimal microphonics, which there hasn't been the entire time I've had these. The thickness combined with the slick rubber also prevents tangling of the wire, which is VERY nice in my opinion. I really hate when wires get tangled and knotted, and it's really nice to be able to quickly pull apart a knot with this type of wire, especially since the loop radius can only get so small before springing back out. The package comes with a 1/4" screw-on adapter for fullsize jacks.
Speaking of the that, these headphones come nicely packaged in a box resting on a translucent plastic headphone stand. It's not very sturdy, but it could easily be used as a stand/display for these headphones, especially since they fit perfectly and have felt on the bottom/sides as well as a groove for the cord to fit into.
The AD900s are the closest I've heard to real sound, but I do realize there are much better headphones out there. To me, though, spending around $200 for a very nice pair of headphones is very satisfying, and I don't think I'll be looking to upgrade these for a very long time. I don't have too many comparisons to make, but if I had to give it some sort of score, I'd rate it 9/10, only because I haven't heard anything better (and I'm afraid to!) Anyway, I hope I at least gave some curious people an honest opinion on these superb headphones.