I sometimes had problems with some usb chains on my old mac pro and it nearly always had to do with too little power delivered to some device, which became unstable, therefore my first question.

ok, as i also have a bayface pro, i plugged it in additionally to my digiface (btw. my hub is also passive) - both seem to work ok?
the babyface pro only requires 100mA according to the system report, can this be true? i didn't connect any mics, but even switching phantom on/off does not make any difference, maybe this changes when the power is really needed?

Interesting - so the BF Pro obviously uses much more.

 Power supply: USB bus power or external power supply
 Typical power consumption: 2.9 Watts
 Max. power consumption: 4.6 Watts
 Current at 5 V bus power operation: 600 mA (2.9 Watts)
 Current at 12 V external power: 240 mA (2.9 Watts)

when I first got it, i plugged it in into my macbook running on battery for testing and had quite some problems with stability, it went out and came back again, this might explain why. (The aftermarket battery in my MBP was also wrecked - suddenly only half of the charge was left and it went out suddenly ... had to be replaced, but maybe just bad timing). Running on the 60w poweradapter bus-powering the BF pro was no problem.

So you tell the OS it uses 100mA, because when you provide the real value, the OS will refuse to use it, because of theoretical power shortage on the usb bus?

Does the digiface report the correct value? i find this very eye-opening and interesting. i was very naive thinking, that there's something in the usb hardware in the computer, that really _measures_ the current