USB 1.1 has enough bandwidth to run two channels into the PC, and two channels back to headphones via the audio interface. But yes, the latency is extreme. Which is why USB devices like Digidesign's Mbox line have a "mix" knob, so you can rout the inputs directly to the headphones before it gets to the PC.Bill Mecca said:USB is pretty much a one way stream, so even if you did get the input signal back to the headphones thru the USB device the latency would be insufferable.
USB 2.0 achieves higher throughput by buffering the data stream, which is fine for cameras, and scanners, and the like, but not so fine for recording.
Serious recording devices use PCI/(X)/(e), or Firewire.