The urge to compare the KEF M500 to the Sony MDR 7520 became so intense that I ordered a pair from Amazon with overnight shipping on Friday. Some quick first impressions of the 7520's..
Packaging/Presentation: The box looks durable enough but what a hassle unpacking the headphones, even more of a hassle to package them back up. Way too much plastic to deal with.
Build Quality/Aesthetics: Solid. Photos of the headphones don't do it justice.
Comfort: Very good. Was able to listen to the headphones for three hours with no discomfort issues. The clamping force is strong but not too strong.
Isolation: Good enough.
Sound quality: BRIGHT! The treble output can be borderline jarring. Music subjected to the loudness wars is especially fatiguing. Overall I prefer the sound signature of the M500. The M500 is more balanced across the entire frequency spectrum. I did most of the 7520/M500 comparison on a MacBook Pro (unamped) listening to mostly Indie Rock with a combination of apple lossless and aac 256 audio files. The 7520s sound a lot better when plugged into a HeadRoom Ultra Desktop Amp that I use with an iMac. The 7520 still sounded bright but the bass and the midrange sounded a lot more fuller.
The 7520s are the most analytical headphones I ever listened to. Recording flaws become very apparent especially floor noise. The bass is where I want it to be on the 7520, very controlled, not too much, not too little. It's hard to gauge the midrange because of the brightness of the treble. The 7520s probably are less than ideal with my audio setup and the type of music I listen to. I have until the end of January to decide if I want to keep the them. Gotta love Amazon for their generous return policy.
Thanks for your impressions :) Interesting that you call them bright. I did find them to be extremely clear sounding (as in other headphones sounding veiled), but perhaps that really is what brightness is all about. I agree on the analytical part, you will hear everything in the recording. But that makes sense, given that the target market for these headphones are audio engineers and such, who *want* to hear everything in the music when mastering a recording.
Also, I think the 7520 scales well with a better amp/dac.