Total posts : 45366
Sorry, but I don’t build and sell but would be glad to advise if needed.
Perhaps your experience with the RCA phono connectors differs from mine but I have had trouble with them over the many years of using them. Unfortunately they do not fail hard and I usually catch problems when I notice one channel is not at the same amplitude as the other or I notice distortion. Wiggling or resetting the plugs makes the problem either better or worse in which case the cable goes to the trash. After having some one opportunity recordings ruined in this manner a better means is being implemented.
The problem is what to do with equipment which uses RCA phono jacks. It’s not pretty but I open the cabinet and solder shielded wire into the circuit and run it through any vent hole or even the jacks themselves (takes small wire) and solder the 1/4 inch jacks to the whip wire.