From the FAQ "The S/PDIF receiver supports the standard PCM rates 32kHz/44.1kHz/48kHz plus 96kHz with upto 24 bits, whatever comes from the source. The S/PDIF receiver can also be configured to support 192kHz. We are not sure if 192kHz will be enabled in the first firmware version."
So it works in the digital domain and if put between pre and amp it would involve conversion from analogue to digital and back again. It would probably be better done from a computer or transport source via USB input and use this as the DAC. I think that would be a better location. In fact, it has a volume control built in so if you have a one source digital system you wouldn't need a preamp. Cool.
But it doesn't work for us vinyl heads (and you've been assimilated).