In fact Novation was the first company with a total integrated synth which is the Novation Remote25 audio or X-station or whatever it was. It uses a usb connection too, sends the synth's output directly to the host sequencer like Virus TI and the synth acts as an audio interface too. I guess Access use the same company's usb driver which Novation use too.
http://www.usb-audio.com/