In terms of phono preamps with digital outputs:
Pro-Ject A/D Phono Box S
The Project website suggests this is built for the kind of purpose you are after. However there is a rather cryptic reference to the USB connection having to be active for the optical out to work... Quoting from their site:
But A/D Phono Box S has also other significant features: It allows to connect a turntable, tape deck or other source to devices which has no line input. Today some AVRs have only digital inputs and connecting of the turntable or tape deck seems to be impossible. The answer is A/D Phono Box S, which allows the connection of analogue devices via S/PDIF optical output. Optical output is only available, when USB connection is active.
Another thought is would something like: NAD PP4 phono preamp USB out > USB to optical converter > optical input work?