I don't have a 5900 in home (YET, one more week) but have heard from 3 seasoned audiophiles whose ears that I trust that the redbook performance of both players is EXTREMELY hard to tell apart, though SACD is a bit better on the 5900, and video is what the 5900 does best (if anyone cares...). If that's true then the 8400 would be an easily better player for music from my listening to it and the 2900. Actually, underwood wally, the modder for these players, just posted an ad here stating that the 2900 and 5900 sound identical on redbook, which is pretty bleak for the stock machine, me thinks, and hopefully the mods really do wonders. I don't mean to upset any happy owners of the Denon's, it's all just my experience and opinion, and if you're happy with the sound, more power to you! It's a personal hobby, there is not a right or a wrong when it comes to art!