Hum when recording audio via audiophile usb, HELP!!

Archived from groups: rec.audio.pro (More info?)

I have a dual 1.25 G4 Mac with an audiophile usb. I use Logic express
in Tiger OSX10.4. Sometimes (not always) when I record guitar via my
PodXT, connected to the audiophile, I get a hum when I press the record
button in logic, that I can only get rid of by turning of the
audiophile device. When I record vocals I use a studio projects VTB1
mic preamp connected to the audiophile and the same thing happens
(always). Usually I can do one take and then at the start of the second
take it starts, from nothing and quickly progressing to the hum that
stays the same when it has reached a certain level.
I need to quit logic turn the audiophile off and on again, restart
logic and then I can do another take. Very frustrating.
My ideas are:
-It may be something with driver for the audiophile (I am not to eager
to update because I also still use OS9 and CubaseVST and I'm afraid an
upgrade will cause trouble!)
-Some sort of ground loop
Help, it's driving me crazy!!
Thanx