I guess its for listening to music? If so, if you use winamp like I do, try dfx, it does a decent job of enhancing the output. You can also configure several profiles, especially for headphones.
i tried dfx, its pretty good. the only thing im battling for right now is a wider sound stage. i like foobar's configurability and dsp plugins.
yes, the headphones are for music only.
right now my benchmark audio is the 24/96khz flac of NIN the Slip. there are lots of nunances in the audio that with proper tweaking can sound amazing.
another good benchmark for audio is Gorillaz - Dirty Harry. i should be able to count the voices in the kids chorus.