I just paid more for these (the 250 ohm)on Amazon not too long ago. I love these headphones ! I was able to compare the 990's (too bright) , 770's (too thumpy, small soundstage) and the Senn HD6xx (too dull)--- and these won out for "me". Sure--the closed back 770's had a little more bass response/reflex, but I found myself gravitating the these more often and once I quit the annoying side-by-side comparisons, I found these to be the most enjoyable for overall listening. The soundstage is just right and the bass response is tight and not overemphasized (and I have tone controls if I "need" more thump). I'm running these through a home stereo Adcom GFP555 mkII preamp---- and sounds great !