headphone amp

Huh? Get the headphones first.

If you are happy with accurate pro sound then the Sennheiser HD 25-I-II is extremely dynamic and detailed (love percussion on these babies) and the closed cup on tehse headphones will cut out leakage and noise from the environment (-17 db extra noise floor!). The other pluses are that although they are very expensive and look like crap - they work GREAT with a lousy source - like an Ipod, laptop or a V-drums module, furthermore, - nobody will steal them from your travel seat when you go to the washroom...

I'd check the headphones out first - the one I recommend above have a very high sensitivity (db/Volt) so they do not need to be driven hard and a high cost headphone amp is of less criticality. Of course, if you go for some other types of high quality headphones then you may need to factor in a $300 to $500 headphone amp like the Benchmark HP2 or many others...(example - my AKG 240's NEED a good headphone amp to sound their best)

Agree with Shadone. ID the phones you like first. Head amp matching (impedance and other factors) is critical.

In case you end up with Sennheisers, specifically the 600, I've had really good results with the CIAudio and the Bellari.

If you are not going to buy some dedicate/high end headphones, but just some budget ones, which doesnt have to be bad at all, I would go and buy some portable headphone amp, like GoVibe Magnum, or GoVibe Petite with DAC, which I own, use with Audio Technica ES7 headphones and pretty happy with the combo. Another headphone option, which goes very well with GoVibe amps, would be Grado SR225i or SR325i headphones, check it out up here for amps http://www.unclewilsons.com/shop/step1.php?number=594.
Having portable amp allows you listen to your files, using laptop or mp3 player, at much better level everywhere you want, insteat of having desktop one, which can be used at home only. But if you still want to buy some budget desktop one, go and check Darkvoice http://www.audiophilechina.com/products1.asp?S_id2=2&s_id=25 or Little Dot amps, check Google/Ebay as well.

Check Darkvoice up here http://www.audiophilechina.com/products1.asp?S_id2=2&s_id=25