The control panel tells that the Sync Source is Internal. (Please click the image to enlarge.)
% ls -l /proc/asound lrwxrwxrwx 1 root root 5 Apr 24 20:24 Orpheus -> card0 % cat /proc/asound/card0/firewire/clock Sampling rate: 44100 Clock Source: External (MSU-dest: 7) % cat /proc/version_signature Ubuntu 3.19.0-15.15-generic 3.19.3 % cat /etc/lsb-release DISTRIB_ID=Ubuntu DISTRIB_RELEASE=15.04 DISTRIB_CODENAME=vivid DISTRIB_DESCRIPTION="Ubuntu 15.04"
But, the proc asound file says “Clock Source: External”, which I do not understand.