I see you're using the kxstudio packages repositories... so for having it all as easy as possible, that I'd recommend for you to install cadence as the kxstudio's borne and native jack-control application, then just run it to start the jack-audio-connection-kit server and, if all goes well as possibly, start the pulseaudio bridge as well--only after that you may then run qtractor and have browser sound all the time.
re. broken pipes error messages: these seem to be some apt-get messages on package retrieval for local installation... i'm afraid i have no definite idea what's wrong there or else--i don't use debian at all, so this might not be the right place to ask on that subject--for all kxstudio/debian related questions, please use their proper forum.
I see you're using the kxstudio packages repositories... so for having it all as easy as possible, that I'd recommend for you to install cadence as the kxstudio's borne and native jack-control application, then just run it to start the jack-audio-connection-kit server and, if all goes well as possibly, start the pulseaudio bridge as well--only after that you may then run qtractor and have browser sound all the time.
re. broken pipes error messages: these seem to be some apt-get messages on package retrieval for local installation... i'm afraid i have no definite idea what's wrong there or else--i don't use debian at all, so this might not be the right place to ask on that subject--for all kxstudio/debian related questions, please use their proper forum.
hth
cheers