[bl42ed0]

The 560 seemed too plain to me whereas the 500, I enjoyed the highs and mids quite a bit more. Of course it helps that I listen to a lot of electronic music with female vocals. My question is this: I'm looking for a permanent (HAH!) upgrade from my 500. Would the TH-900 give me more of the 500? or the 560?

 

[iKhaos]

I've owned the TH900 for about a week.
Succinctly, the TH900 has a v-shaped sound. Clarity is great, treble sometimes bordering on sharp. Bass is very strong. Never boomy though, very clean. The mids are slightly recessed.
They're fun sounding if you're into that. Definitely endgame "closed headphones." They're supposed to be closed but I'd call them more semi-open. They leak some. Soundstage is decent.
I think they'd be pretty great for electronic music. They are a beautiful pair of headphones but not my taste. I don't listen to a lot of bassy music. I listen to a lot of music where vocals take center stage so the recessed mids put me off. Also not worth the price for me. YMMV.

 

[rgs9200m]

Yeah, I like my TH900 much more than my 560. The TH900 has a neat combination of silkyness, glossiness, liquidity, impact, and decent detail. It's not analytical, rough, sandpapery, or anemic sounding. Is it OK to say musical. And really swings and carries you on a wild ride. It's excellent with lossless music. It's not brutal, but really hits hard. The lossless input keep it from sounding thumpy. Just subjectively, the TH900 resonates emotionally with me and I don't want to call it a day with them. 
The HD800 and 560 don't do this for me. I have a hard time choosing between the TH900 and the HE1000 as a matter of fact. Although they have different signatures, they both hit my primitive brain in ways that I call them equal in overall level of enjoyment. (Specifically, the TH900 mids and vocals are more liquid and have more bloom, but the HE1000 mids are more detailed.)