Hi! I'm writing, becasue I recently have a problem that I think is closely related to JACK. A few days ago, suddenly I was unable to play or record anything. I found out that I can use my soundcards in Ardour only if I use ALSA as a backend - not JACK. Running JACK with 3 different audio interfaces everytime spawns 32 in / 32 out channels in the "System" JACK hardware clients - and none of that works. I thought there's a problem with my system installation, but the same problem occured when I booted up an AV Linux LiveCD - and that really confused me. I described the issue in more detail on LinuxMusicians.com forums: https://www.linuxmusicians.com/viewtopic.php?f=27&t=16527 I'd like to invite you to take a look. - unfa