Cool! Look what I found for USB:
http://wiki.linuxaudio.org/wiki/list_of_jack_frame_period_settings_ideal_for_usb_interface
-------- Will Godfrey 02:42 Wed 02 Mar --------
I simply could not get off to sleep tonight, so got up and decided to have
a play around with yoshimi.
Just for a laugh I set for 16 frames Jack & Yoshi @ 48kHz (that's 0.667 mS)
then ran the example file 'Out_There.xmz', but used the original Rosegarden
project, so had the overhead of Rosegarden too.
I got a total of 3 inaudible Xruns spread through the busiest part of the
piece, with a peak DSP load of 36%.
Machine details:
3.1 G, 64 bit, dual core Intel (this is my 'office' machine, not my DAW)
Debian testing, kernel 4.3.0
I think I'll have to consider dropping the minimum buffer size to 8 frames :)
