I have the same headphones and two headphone amps - cheap and really cheap - the new FiiO 5 is $20 bucks at Amazon - looks exactly like an ipod shuffle - charges from USB. And some other nice one that was $60 bucks - probably not made anymore. I bought cheap ones because I need portable - I used them to drown out the dentist drill for some long procedures.
The one piece of advice I keep harping on - PLEASE use the LINE OUT audio from the ipod jack, NOT the headphone mini output when connecting to any amp. The headephone audio out was not designed to be amplified impedence and gain is all wrong. The line out will give much better results - plus you leave the ipod on min volume conserving battery. If you use the headphone output you'll be in the same place - having to turn the amp output all the way up and also the ipod output up really high. (wasting ipo battery) Problem - its really hard to find a decent ipod output jack cable - I've made my own.
The one piece of advice I keep harping on - PLEASE use the LINE OUT audio from the ipod jack, NOT the headphone mini output when connecting to any amp. The headephone audio out was not designed to be amplified impedence and gain is all wrong. The line out will give much better results - plus you leave the ipod on min volume conserving battery. If you use the headphone output you'll be in the same place - having to turn the amp output all the way up and also the ipod output up really high. (wasting ipo battery) Problem - its really hard to find a decent ipod output jack cable - I've made my own.