If you really want to know......
I bought the used pas 4i from Frank, after bad jacks were found, new jacks were provided by Frank, labor's on me (it took me about four hours to replace them all).
I am not complaining (because I am a nice guy). But with my years of experience in audio, low end and high end, I don't believe the preamp was abused by someone who didn't know what he was doing, it was more like excessively used, like people have a lot audio pieces, they like to swap them around every now and then, or it might have been Franks testing piece, who knows...
I know this because I've done lots of equipment swapping, cheap or expensive cables, Kenwood, Technics, Nakamichi, Cary, Audio Research, Adcom... and have never had problem with any RCA jacks.
After I replaced all the RCA jacks on the Super Pas 4, I actually disected one of them and examined how it was made, my own conclusion is the dielectric's kind of soft, metal for the center female connector is thin, in comparision of the Adcom's, I actually disected an Adcom jack, which was the type that soldered right on the circuit board, the dielectric seems harder, not sure if the metal connectors are of the same thickness, but it was made in a way that provides some spring action while gripping onto the RCA male connector, which would provide more tolerence for larger connector pin, but like I said, the two cable that I measured had about the same diameter.
If it's still not credible enough for some of you AVA deciples, ask Frank. I am tired of explaining.