A cheap amp will give you distortion at higher volume levels, so if you like your music to sound like garbage, then by all means... sorry, i'm a little bitter about a portable amp i recently bought on ebay for $30.. sounds like crap but on the other hand i did only really get it for watching movies on the xbox so that i can adjust the volume level.
If you're looking for a deeper, warmer bass with these headphones (or any other headphones).. get a tube amp like the bravo audio ocean or whatever fits your budget.. tube amps give you just that... or so i've read... i've never listened to one before :(
You got the wrong headphones though if you are after that rich, deep bass. You can equalize and get a bass-head amplifier all you want but it just won't sound right. The driver isn't made for it.