Mark Levinson 23.5: camac or RCA?

Much easier to buy a RCA female - CAMAC single piece gold adapter and keep your RCA cables untouched!

The original Lemo adapter sold by Mark Levinson is very well built and will not degrade the signal more than the thousand tweaks you are not using in your system :-) . IMHO using the adapter is better than re-terminating the cable with Lemo connectors that usually are not suitable for thick audio interconnects.
Anything you change can degrade performance, but the real question is how much?

Camac / Lemo connectors are used in nuclear and laboratory instrumentation mainly because they are small and reliable and can be inserted and picked easily many thousands times.
The same hardware that costed a few bucks for laboratories was sold for audiophiles at much higher price. Although there is no firm evidence that they sound better than other audio plugs, they do not break the earth path before the signal one and are self-locking.

To clarify matters, Levinson used single pin Lemos for unbalanced signals, Cello used Camac three pin ones for balanced signals and Krell uses four pin Camacs for cast (current mode) signals.

If you do not mind the extra work and mutilating the original back plate, fitting a RCA connector to the amp is the best solution. But if you accept that a Cardas RCA plug sounds different from a Neutrik the choice is not easy ...