OK, i know this thread is pretty dead but i just thought I'd update it for any poor soul in the future that bumps into it.
I brought a Sampson S-Amp. No particular reason, it's cheap i guess was a reason. So i thought i'd test the water with it.
The headphones are much improved as a result, bass is nice and audible now! And the levels fine now.
Not sure how i rate the Amp, to be honest anything I say about it's probably just going to throw mud in the water, it's served its purpose though.