Hmmm.
I'm on debian, so I can't speak to the whims of Gentoo, but let's play a bit.
Do you have the alsa soundblaster module on your system? (you could try "locate snd-emu10k1.o").
If so, can you load it? ("modprobe snd-emu10k1")
If so, can you play anything with it? ("aplay afile.wav")
If so, things aren't looking too bad; maybe KDE is set up to try and play to the OSS modules and you don't have compatibility set up.
A responsible gentoo'er can probably help more, but at least we can get more of a baseline on what the trouble is.
Oh yeah--and what kernel are you running? ("uname -r")
-->VPutz