Hi, I have a pair of Denon C751's that have replaced my broken Sennheiser CX-300 II's. When I listen to my iPod using either of these earphones, I get some slight distortion up in the top end. It seems to be worse when there is a lot going on musically, like guitars, drums, bass, vocals all going at it in rock or punk music. I know a lot of people will say the iPod has bad sound quality, but I also do get the same distortion when using the earphones through my pc, which outputs sound using the on-board sound card (I know!) through an optical cable to a little Kenwood hi-fi system. The distortion seems very slightly lessened this way, but it's hard to tell. So. What would be causing this? Will this be fixed by using a decent headphone amp? At this stage I have about AU $350 to spend and am wondering whether to get a headphone amp like the Meier Corda 3Move, which I would use at home and sometimes away from home, or a new pair of headphones for home use only, like the Grado SR325i. Cheers.