I have experimented a lot with my opticalRendu (oR) setup.
1. Power supply quality makes a bit difference. I feel that the Sonore Audiophile Power Supply (SAPS) is a great match for the oR and the opticalModule (oM).
2. The type of SFP matters a great deal to the sound quality. Some sound digital with a low noise floor and a relatively flat soundstage. Others sound more natural, with better timbre, more euphonic with a better depth in soundstage. The best SFP I have that exhibits the latter is the Cisco SFP-10G-AOC1M. I prefer that over the others I’ve tried. And yes: please be very careful and buy the original one - the ones from China on eBay appear to be fake.
Soon, I’ll be placing my oR/oM setup with 2 SAPS, SFP / fiber up for sale to move to the signatureRendu.