I own a Shure 545S.
I have the standard Shure cable with Amphenol MC4M at one end and a female XLR at the other. I also have a A95A line matching transformer that has a male XLR at one end and appears to be missing its other end. It terminates in a male screw type 1/2" fitting with a center contact. Any hope of getting the missing fitting that would end in an RCA ?
The connector that you are talking about is an Amphenol MC1F connector. We offer this as a fitting to 1/4" connectors, but do not offer it to an RCA connector.
You might want to contact Amphenol or Markertek to see if they have an adapter for you.