I've had my Sennheiser HD428's for a while and I think the SQ on them is pretty good, I modded them for more bass and they sound pretty damn good to me. I listen to mostly dubstep, DnB, and rap, some alternative, pretty much a little of everything. Just yesterday I ordered a pair of Superlux HD681's. To the people who have experience with both of these headphones, how much of an improvement in the sound quality am I going to hear, especially the bass (quality and quantity)? I'm listening through an iPod touch 4th gen (no LOD or amp, YET!).