I'm using a Roland R09-HR, a Roland R05 (which is pretty much the same I guess) and my Samsung Galaxy Note 2 as my portable player devices. My headphones are the ATH-M50 and the EW9 from Audio Technica and the RH-200 from Roland. I'm solely using them on the go on my way to and from work. I would like to improve the sound and I was wondering if there is a decent but reasonable battery powered headphone amp which would be able to do the job. I would also like to know what kind of improvement I'd have to expect. Is there anybody with similar gear who has experience with that? I'm listening mainly to Rock music and also some Electronica like Ibiza House. I'm trying to avoid MP3's, so pretty much all I have are 16 Bit 44KHz wave files.
Thanks a lot!