I'm pretty sure most everyone knows (or can easily guess) what a "USB Converter" or "USB Interface" is relative to audio.
But if the model number has to describe it exactly then the only choice would have to be
Bryston Digital 24-bit 192KHz Asynchronous USB to AES/EBU and S/PDIF Converter
All those outputs could easily be summarized to either digital audio outputs or S/PDIF outputs.
James uses the description USB to SPDIF. Why shouldn't that be used (BUS-1)? It describes the device purpose in detail withouth having multiple meanings or beeing to vague.
USB Interface or USB Converter only makes sense for you if you have stereo as a special interest. If I say to the guys at work that I just bought a USB converter for my stereo my guess is that absolutely noone would understand that it is for the purpose of converting USB to S/PDIF because they are only mildly interested in stereo. They would think USB to Analog (as in DAC), USB storage or something like that even if they know it's purely for audio usage. I would actually prefer a totally random name, like "Hiface Two", before the multiple meaning terms USB Interface or USB Converter.