Audiophile Grade RCA Input Suggestions?

I put the link to inspire you to get the OEM part.
It's likely a custom run.

I agree that I think you're stuck with stock if you're not willing to build your own solution with more standard connectors. I've liked the WBT low mass RCAs I bought while switching everything I could over to pure silver, but haven't found the influence to be huge. Based on my modding experience, I'd spend on good film & foil caps, a power cord, or solid core silver internal wiring before upgrading RCAs. 

How can you tell if it is just the RCA connectors that seems to be shorted and not actually in the electronics passed the connector itself?

Doug,

I used a multimeter across the ground and signal connections on the input component to verify that there is an internal short. 

I performed the test out of circuit as well, to make sure no other parts of the circuit were messing with my reading