Ik denk dat je jackd nog moet installeren en activeren. Zit in Synaptic.
JACK Audio Connection Kit (server and example clients)
Low-latency sound server. JACK allows the connection of multiple applications
to an audio device, as well as allowing them to share audio between
themselves.
See <http://jackit.sourceforge.net/> for more info.
This package contains the daemon jackd as well as some example clients.