strange USB audio issue

[CJP2]

I put this post up elsewhere but figured I should move it to this forum.

 

Since my upgrade to 10.6.4 (now at 10.6.6) I've had issues with my audio. Not wanting to deal with crappy onboard audio from the beginning I've been using an external DAC via USB since 10.4. It seems that when my storage HDDs spin up from an idle state it kicks my audio stream off.

 

Interestingly, if I go into Audio MIDI Setup and adjust the Format from 48000Hz to 44000Hz (or vice-versa) it comes back just fine so my workaround has just been to keep AMS open in the dock for a quick fix. I'd sure like to know the root of the issue though and not have to rush over to the confuser mid song or in the middle of a movie.

 

Running vanilla, use BootThink for bootloader on a usb stick, custom DSDT....

 

In BootThinks equivalent of the Extra folder I have:

 

fakesmc.kext

Intel82566MM.kext

IOATAFamily.kext

LegacyAppleAHCIPort.kext

NullCPUPowerManagement.kext

PlatformUUID.kext

 

I've removed AppleVIAATA.kext from IOATAFamily.kext (and of course returned an unmodified IOATA to S/L/E) to rule out any possible ATA controller interference.

 

Anyone got any great ideas?