After about 100 hours of burn-in and a weekend of listening, I'm ready to render my judgment on my pair of the S500s.
The short version: they are awesome.
The slightly longer version:
I've thrown nearly every genre I could find in my library at them and I couldn't find one I didn't like with these. Tracks with a nice bass line definitely profit most from them but I also enjoyed them with something like acoustic guitars or orchestral tracks. Though being on-ears and closed, their stage is not as wide as I sometimes want it to be. In general it's more then sufficient though.
A note on burn-in: Before burn-in I thought they had a veiled sound and some piercing highs but that has now completely vanished. So I would recommend some burn-in if you don't like them immediately out of the box.
When I ordered them, I was a bit wary of the folding mechanism and the general build quality. After having them in my hands, I don't think that there will be any issues in the foreseeable future. They are well build, the materials have a quality touch to them and overall they seem to be quite sturdy.
I have rather large ears, so for me these are on-ear headphones. I used them for smaller and extended periods of time and they never got to the point, where I had to take them off because my ears hurt. Though some times after taking them off after longer sessions, I realized that my ears were a bit sore. I just didn't realized it while wearing them. If you have larger ears and you are a bit sensitive to pressure on them, I would recommend going for one of the ear-pad mods.
I was lucky and got a friend returning from japan to bring these along for me, so I only paid 35€. For that price, these are definitely the best headphones I own (which are not a lot to begin with ). And even if you have to pay the imported prices, these will be a great investment.
Some of the tracks I used (Click to show)
Nalepa - Monday (The Glitch Mob Remix) [nice test for clarity/highs; electronic]
mitch murder - airwolf (cover) [nice steady bass, like the layering in the synthies; electronic]
Christopher Tin - Baba yetu [a.k.a. Best Game Menu Theme ever ; orchestral,choir]:
Beethovens Symphony No 9 - 4 (a.k.a Ode to joy) [Video only for reference, you should use a better version; orchestral,choir]:
Adele - Skyfall [love her voice; orchestral,singer]:
Rodrigo Y Gabriela - Stairway to Heaven [these two know how to handle a guitar; acoustic guitar]: