After a ton of research and scouring over reviews, I just picked up a pair of Denon c551k earphones for listening to music on my iPod and iPhone. I am replacing an older pair of Sony in-ear headphones that I thought were amazing (but can't seem to find anywhere now). One thing that I loved about my Sony's was the bass... great sound without being "muddy" as they call it. I picked the Denon's because everyone talked about the great bass they have. Well, after listening to them I couldn't be more disappointed. I have packaged them back up, unpacked them and repackaged them again probably a dozen times in the 24 hours I've owned them. I want so desperately to like them!!! But the sound is faint, tinny and shallow. And as for bass? What bass? Also, there is a good static "hiss" when they're plugged in and nothing is playing that is really quite annoying. I never had that with my cheaper Sony's. I have read something about this phenomenon of "burn in" time. Does anyone out there think this would make a difference? I have probably less than an hour on them, but not sure if letting them go for a while (some sites say 100 hours???) will really make a noticeable difference. If anyone out there knows these 'phones or can attest to the burn in time, I would greatly appreciate it. Thank you!