USB Audio Output Option Vanished?!?

Hi everyone,
My option to select USB as the audio output device under "Output" in the "Sound" System Pref Pane has seemingly disappeared. I had been using it with my USB DAC unit and left for a week. When I came back and turned on my (late 2008 unibody) MBP, it was gone. Nobody touched my computer while i was gone (no one was home) so I doubt a mischievous relative is to blame. I've since upgraded my HDD and reinstalled my OSX. However, the problem persists. My computer does not show a USB Audio output!

Does anyone have any ideas what the culprit is?

Is this a portable Dac that is battery powered or does it get its power via USB and have
you tried a different cable or USB port?

osxx said:

Is this a portable Dac that is battery powered or does it get its power via USB and have
you tried a different cable or USB port?

Click to expand...

Unless I am mistaken, I should be able to access the USB audio output without my DAC being plugged in. Nevertheless, my DAC has its own power supply. My concerns are that this is a hardware issue with my Mac since with two separate hard drives the problem persists (leading me to believe the drivers are not at fault).

dtk_king said:

Unless I am mistaken, I should be able to access the USB audio output without my DAC being plugged in. Nevertheless, my DAC has its own power supply. My concerns are that this is a hardware issue with my Mac since with two separate hard drives the problem persists (leading me to believe the drivers are not at fault).

Click to expand...

So are you saying the USB port does not recognize external hard drives either
then I would take it to an Apple Store sounds like its hardware.