Recently I did a comparison of HD600, 700, 800, HE500 and LCD-2. Naturally I checked their performance on specific tracks that I chose for evaluating purposes. But I was surprised to see that I was actually able to accurately assess the qualities of each headphone just as well using a 96 kbps MP3. This shouldn't be surprising, after all, we're interested in how the headphone reflects on the source.
yea, that's true, but I've noticed that with nicer headphones, it becomes more unbearable to listen to lower quality tracks as every little subtle distortion is very clearly articulated. I would prefer less detailed, more colored headphones that don't pick up on those finer little issues as well. haahha.