Chris
75 Ohm RCA connectors and sockets have been available in the UK for some years. I bought mine from Canford Audio and my standard BNC crimp worked with them. I think they are offered on Ebay.
I agree 75 Ohm BNC is the best solution if properly engineered.
Most of the issues come from the various manufacturers not adhering to an audio industry standard- none exists- and therefore a mixed bag of RCA sockets appearing for SPDIF inputs.
Making it a field day for the cable vendors !
Technics 1200 tweaked,Ianmac Bearing,DACT DIY Phono Pre, Belcanto CD-2, Engineered Switzerland DIY Renderer, Benchmark DAC2, Hypex NCore, ATC SCM40
2nd system --Engineered Switzerland DIY streamer, Sony CDP11,Topping D50 DAC, Hypex NCore. Kef 1point2 speakers. Ianmac Filters