It drives my Sennheiser Amperior easily.  Admittedly, the Amperior is easy to drive. The sound is very good from 320 Kbps MP3s.  The FM radio is much better than the one on my old LG Optimus T.  The ergonomics are also much better, but this is partly a matter of taste. Still, I wish there were a version of PowerAmp for Windows phones.

My uncle bought a barely used one for just €20, so it is a great deal even if he just use it as a dap then. 

god for 20 euro thats a super steal

Hmm, funny, because my opinion is the direct opposite. Bought the Lumia 635 as a replacement phone between my HTC One (m7) and One+ One. I actually found that it sounded a lot worse than those two phones, which I compared it directly to. To me, it was such a downgrade that I actually refrained from listening to music on the go while having the phone. If applicaple, I used the HD25's, the B&W p5, AKG K518 aswell as the philips sx1's. Mostly listening to rock orientated music but everything from Opeth to Alt-J.