High-pitch noise coming from external speakers when I play a file
I just bought a pair of the Rokit 5 external speakers. When I plug them into a Mac Pro (Tower) I get a high-pitched hum from the speakers each time I try to play a sound. So if I go into System Preferences/Audio, and I try to play a sound, the high-pitch is heard as the sound plays, and for a second or two after, then it goes away, and is heard again each time I try to play a sound. Same with when I play something thru iTunes or any of my audio apps.
If do the exact same thing playing from a Macbook, I do not have that problem at all, the sound is nice and clear with no high-pitch sound.
I have the speakers plugged in using 1/4 inch jacks to an external sound card (MBox), and this audio card is plugged USB into the Mac.
Has anyone else experienced this, and have you fixed the problem?
Thanks.
Regards,
Paul
Mac Pro, Mac OS X (10.6.8)
