First of all, these are two very good headphones (ATH-W1000 and Beyerdynamic DT831), but they are different. It was no problem to discern between the two.
The Beyer DT831 is bright, no doubt. But it DOES have great, deep bass.
It think it's the midrange that is the problem. Somewhere between midrange and very deep bass. Sometimes it's like a voice lacks...something...richness perhaps. Maybe that's why some many says they find the 831 lean.
I suspect the 831's connected to a good CD-player and a tube-amp would be very interesting...
I have a test-CD meant for setting up a hometheater. One track is for testing out the subwoofer, it's just a sine wave that sweeps from 160 Hz to 20 Hz with voice announcements of the frequency. Both phones must have an incredible flat low-frequency response curve. I can't hear any blooming or "humps", but I CAN hear the test tone all the way to 20 Hz. Most impressive.
The ATH-W1000 are a more balanced headphone. It's very detailed, but not too bright. It sounds very complete, from top to bottom, although I hope the deepest bass loosens up a little.
You don't get tired of listening to the W1000's, in more than one way...:-). It's more forgiving without sacrificing detail.
The W1000's costs over twice as much as the DT831's. Is it worth it? I think so. It's exotic, great looking, comfortable, well-engineered and suits most music-styles. It's just more complete.
I hope this has been helpful in any way.
Credit: JensL, head-fi.org (Full review)
