I've listened, if one has a dac, no difference, perhaps there is a very very very very very very small difference between various players if one uses the regular audio out... but to me anyway, the differences are so minor that sound quality doesn't need to be the top priority. For me, flexibility in playback is tops - if I can't play my music, it doesn't matter how good a player is in all other categories! So Cog or Play wins out. I prefer Cog because it is more stable and has a better update schedule. Seriously, for me, if iTunes could do FLAC without the hacking I've had to do to get them to work, I'd use it exclusively on my Mac. Under windows... foobar and no other. Under linux, sadly there isn't much out there that really compares. Quod Libet is a decent player if it was stable, but it's file tree view doesn't work all the time. Amarok is far too bloated and looks terrible, Songbird is unstable (though getting there) and most other versions fall short from the above three, leaving only a Wine'd version of Foobar to get one tapping their toes.