Hi, Im a lot on the road for my job and at the hotel in the evening Id like to practice. So Im currently looking for some gear I can take easily with me. I got a Hohner headless bass and Sennheiser HD-25 SPII (60 Ohm) headphone. Now Im looking for some kind of a small form-factor headphone pre-amp (or something like this) that sounds good w/ my headphone. An aux-input for an mp3-player would be nice. Do you have any suggestions? Thanks!