There’s someone who makes RGB SCART cables for the DC with sync cleaner on E-Bay, so that part would be solved. I’ll ask him if he’d be willing to make all the Extron cables I need and then try with Keene, but I’m about giving up.
When I was deciding the purchase of the Extron interface (which was really hard to find in my country), I checked the RGC site and the input/output didn’t seem to be an issue since not only did they have the cables available, they even had notes suggesting their use with these interfaces. Now it seems that they even advise against this, and the output cable/adapter isn’t suited for TV sets by themselves (I guess PVMs are OK?).
Adding an UMSA to the chain is nuts for this only purpose of mine: Extron 30 € + input adapter ~25 € + UMSA 30 € + BNC-DB15 ~15 € + SCART-SCART 25 €, total ~125 € not counting the sync cleaner console cables… Not worthy.
Thanks for clarifying.
By the way, I find it funny that an Extron does support sync-on-luma S-video but doesn’t sync-on-luma RGB. Has this really been tested and confirmed?