USB Microphone on Mac OS X Host, Win7 Guest gets only static

[KCBaltz]

VirtualBox 4.3.20
OS X 10.10.2 on MacBook Pro
Win 7 SP1

I have a Win 7 guest configured with Intel HD Audio and I'm trying to get it to let me use my Cisco IP Communicator soft phone with my Plantronics USB headset. Everything works if I use the built-in speakers and microphone or a wired 1/8" headphone set, but when I use the USB, only the audio out works. When I listen to what the audio IN is receiving, I hear bursts of static.

Based on another thread on this forum ("[Solved] XP/Win7 guest without microphone ?"), I'm guessing the problem is that the USB Headset has only two sample rates, 8khz and 16kz, but the Win 7 device is expecting 44.1kz. Neither the guest nor the host gives me the option to pick something compatible with the other (Host gives me the two 8 and 16 choice, guest has the option greyed out).

Any suggestions?

[KCBaltz]

Bump.

[socratis]

If you've already tried to set up your USB microphone using the /Applications/Audio MIDI Setup, I don't think there's more that you can do.

[KCBaltz]

I was afraid of that. My guess is that what's needed is for the driver in the guest to allow configuration of the sampling rate. Right now, it seems to be fixed at 44.1k. I don't know how easy it would be to modify the driver.