I tried the Hifiman 901 (again) at the Tokyo Headphone show, I tried it quite a while back also. I enjoyed it both times.
I am not sure how much my initial impressions have changed as digging up my past post would be...
I tried it just now.
Color me impressed.
AD8066 and OPA627AU -clear, punch and clarity.
Found myself nodding my head which is a good sign.
Also tried Muse8920, Muse01.
The op amps arent fixed so you can switch them about.
Iphone 5 supports WAV. Its even in their tech specs on the iphone5 page on the apple website.
FLAC - no need to jailbreak there are many apps that enable you to play FLAC on your iphone, some even with great eq functions. Flacplayer,...