Hi-
I’ve owned several streamers, including the microRendu and some much more expensive ones. Also expensive power supplies.
Conclusion: they don’t really help SQ (unless your DAC is a very poorly implemented one).
The RME is the opposite - high level engineering, so I’d be surprised if in a non-sighted test you can hear any difference with a streamer, even a good one. I don’t think your dealer can back up his claim of clock/jitter issues with a measurement, can he? Ask him to loan you an mR or similar device and do a non-sighted test.
That said, there are some reasons to get a streamer: multi-room use, get the server out of your listening room, or if they give you software implementations you wouldn’t get otherwise. The Sonore streamers give you lots of options for different kinds of software playback and work well. So an mR is worth it for that. It’s OS is good and Sonore updates it and has good customer service.
I went over to a fanless NUC running Windows as a streamer and have Roon Bridge, Squeezelite, and HQP NAA loaded on it. Sounds the same as an expensive streamer to me. I mostly use Roon, and sometimes switch to the other SW for various reasons.