[LAU] Kmix + jackd strange behaviour

Hi, I have updated my sidux notebook to ourea recently. I now have kernel 2.6.27-4.slh.2-sidux-686 and RT kernel 2.6.26-6.makke-rt11.1-sidux-686 installed. I have installed binary NVIDIA drivers as well (for both kernels) to get xinerama running with my GeForce 6100 graphics card. The nv xorg driver was no option because it does not support dualhead. Although it seems to me as if it was a success, there seems to be a problem with KMix, which is the gui mixer application for alsa. I want to connect an external USB audio card to my notebook when I make music. When I do that, Kmix offers a popup menu to select between onboard intel-hda sound and external USB card. This is fine, but strangely enough, my audio works (and only works) when I select the external USB audio settings in Kmix before starting up jackd. Even if I know for sure jackd (actually, I am doing this via qjackctl) connects to the external USB soundcard, a test with amarok to use jack for audio output fails, if I do not chose external USB in Kmix. So no matter I have chosen the proper audio connection in qjackctl to connect to external USB card it will not be used and does not work unless I select external USB card in Kmix before connection. If I do not do so and Kmix shows settings for internal onboard sound then I can connect qjackctl to external USB card but it is not used - amarok plays via jack and plays on internal onboard sound. So my question is: in which way does Kmix influence the audio settings of jackd? Where is the link by which it is interfering with the settings in qjackctl? It also happens that I cannot stop jack via qjackctl. It simply hangs doing nothing. In short form: 1.) -> Set Kmix to display onboard sound settings, -> Set qjackctl to output to external sound card, -> Set amarok to use jack for audio output, -> amarok plays via onboard sound. 2.) -> Set Kmix to display external USB sound settings, -> Set qjackctl to output to external USB sound card, -> Set amarok to use jack for audio output, -> amarok plays via external USB sound card. Could it be a problem with the hotplugging of USB hardware? Thanks for any hint, Crypto.