Preamp recommendation

Yes. I recommend not subjecting your two channel stereo to multi-channel dreck. If you want lots of channels buy a HT receiver. Put the money you save where it will actually get sound quality results: stereo.

https://www.hifi-advice.com/blog/review/digital-reviews/spdif-dac-reviews/anthem-str-preamplifier-and-power-amplifier/

STR Preamplifier and STR Power Amplifier with the Anthem AVM 60 (near the end of the link below)

https://hometheaterhifi.com/reviews/amplifier/power-amplifier/anthem-str-preamplifier-power-amplifier-review/

I am on an Anthem STR revisit so I am coming across these links.

That would be called a surround processor. Check out Arcam they have a nice one.

If you like the Bryston sound, the SP3 processor is likely going to be an excellent candidate.  It has fully discrete Class A audio stages for BOTH the 7.1 RCA analog input stage as well as the fully balanced XLR analog output stages.  It is likely going to be the best 7.1 channel analog preamp you will find on today's market.