Andy Just to throw my hat into the ring.
I really like the idea of being about to just pass the audio bitstream to an optical audio output.
I do have a 5.1 USB audio device, but that requires drivers to be loaded in order for the 6 audio channels to be processed by the host machine and passed to the device.
Which curiously outputs the audio on 6 connections, or a single Optical port, so it must re-combine the audio which seems very wasteful.
Bit Bashing the audio stream directly to a SPDIF / TosLink / Optical output must require specific hardware because as yet, only my (stand alone) Samsung Blu-ray player offers this feature for connection to a Full Dolby Atmos surround sound amplifier.
My laptop's SPDIF / 3.5mm Optical output only sends out the stereo stream, as do a couple of other USB audio I/O boards I have. (Unless I assign them as a pair of channels from a surround sound stream / source, but that's getting too complicated for this situation)