[linux-audio-user] yamaha rp-u200 and jack: bad sound

Thanks to Clemens,I have 4 channel output from my rp-u200 usb-audio "card" The problem now is bad sound,that is,lots of kind of pops or whatever it's named.Also there is sync problem,sometimes the sound is kind of slowing down. I played back sound with different applications:alsaplayer, ecasound,fluidsynth,terminatorX.Always the same result: When I run jack the sound is bad,but when do the same thing without jack running,direct by alsa there are no obvious problems(except having only 2 channels),so it can't be a hardware problem. Any ideas about the origins of this disastrous sound? I have jack 0.94.0,alsa-driver 1.0.2c,kernel 2.4.20-gentoo-r8. Thanks for help, Jaap van Geffen