Has anyone had success with getting Logitech USB Headphones to work
with FreeBSD? Can someone suggest an audio package or method for
getting this to work. I've tried OSS, but I don't see support for
these.

I have plugged the device in to one of my USB ports and dmesg returns:
ugen0: Logitech Logitech USB Headset, rev 1.10/10.13, addr 2