I compared the graph on GOLDEN EAR.COM, there were some differences in graphs!?
I also have heard k551 does work with Apple's mostly, and not with other devices!
(I use ipod, macbook pro, audiofire4)
Can you help me???
Can't understand why the K551 would not work with "other devices"?
The K551 and K550 are both 32-Ohm.
"other devices don't recognize it" does not really make sense, the K551 should work plugged into just about anything.
I own the K550s and I personally do not have any problems with it's sound, it may not be as warm sounding as my ATH-A900X headphones, but the K550s do have a "clear" sound, to me the K550s are very easy to listen to. Something I could wear for long periods of time.
In general, integrated microphones/volume controls worsen the sound quality. There's a reason you don't see a mic on the SE846 or IE800. The more complicated the wiring, the poorer the SQ. That being said, I hated the K550, but everyone else seems to love it :/