Btw, with my pair atleast, the HD 650 is clearly superior in the mids and highs definition and realism, no question. With these pads, the sound signature has become closer to that of the HD 650, except with less bass emphasis and tighter bass, clearly better soundstage and imaging as well. But the quality of the mids and highs of the HD 650 are definitely superior in every way. Doesn't mean I'm going to get rid of my HD 540's, since the fit is just so relaxing. With the HD 650, I get a bit of ear canal fatigue due to the seal it gives me. But if the others users reported that they ''killed'' the HD 650 in sound, their pair must sound dramatically different. The only thing HD 540 ''kills'' (still too big of a word, but a clear difference nonetheless) the HD 650 in imo, is soundstage and imaging, and bass tightness (but that maybe because the bass is way less emphasized, giving the illusion of tighter bass), but otherwise the HD 650 is the clear winner. Maybe I'm going to upgrade to the HD 540 Gold if I ever come across one in great condition, since they are said to be smoother than the regular HD 540 reference.