Stellar GSD analog 1 can I connect 2 sources

Can I connect OPPO to XLR and phono preamp to RCA of analog 1, or is there another way to increase the number of analog inputs on the Stellar GSD. Would an RCA selector switch degrade the input?

In answer to your first question, no. Analog 1 is EITHER the XLR or the RCA input.

I just tried connecting 2 sources to analog 1 (XLR & RCA) and it worked fine, obviously only one source powered at a time

Yes, you can, with only once source powered at a time. No issues here. In analog one I have XLR to Oppo and RCA to TV. No issues.