If your really looking for bass have you tried checking out the ATH-M50 or the ATH-Pro500 Mk2 from Audio Technica? They are right around the same price as the HD-518. I own the HD-518 and it really gives a very balanced sound with the Senn sound signature of being a little veiled and laid back. In terms of bass, adding volume to these cans will bring it out but without the oomph. Bass is nice and tight specially after burning in.
I recently listened to both the ATH-M50 (which sounded even darker than the HD-518 but gave a lot of bass) and the ATH-Pro500 Mk2 (the highs and mids sounded more clear compared to the M50 but also gave almost the same amount of bass) and prefer the Pro500 because it felt more balanced versus the M50.
As for buying amps versus saving up to upgrade your cans... I'm of the mind that buying better headphones is a better avenue than getting amps which only help by adding bass. Nothing wrong with that, but in most cases unless you buy a ZO2 the bass comes out muddy or loose if you're unlucky or nice and tight depending on the headphone you have. So best advice is, if you can try out an amp with your headphone, do it so you can hear the difference. Then audition the headphone you want and listen to the difference between the two, then choose which avenaue suits you better!
I hope this helps you in any way!
Edited by PKPnytheta47 - 1/5/13 at 5:39pm
