need a new IC cable ( rca )

Secure connections are important. I changed most of my RCA's to Ortofon pure copper with Locking RCA connectors. The best thing I like about XLR in home systems (no long length advantage) with short runs is that the connector's 'lock' in securely.

As for 'better' 'different', I have 3 din phono cables, one vintage, one custom by Pine Tree Audio, one highly recommended Ortofon. various designs and lengths. I switch them, no difference I or my friends can perceive. Slightly loose connection, random balance, anyone can perceive, but knowing the culprit can be tricky, so I rule the connections out these days.

RCA Jack condition is also important, especially vintage equipment. Audio Classics overhauled my mx110z preamp, replacing all 17 rca jacks with new gold plated ones.

Keep the same brand for all IC's, if you like Purist Audio, keep it

Since you like Purist, look for a used pair of Aqueous Aureus (not the early models). There's a major improvement in clarity and dynamics over Museous. Shouldn't be more than $400.

I would look into a used Cardas Clear of some kind. 

I would stay with Purist. But if you can’t wait for a used one to come up I see AZ Matrix II with latest connectors on USAM

Probably closest in sound to your Purist and potentially even slightly better than the Museaus. These would be great for the source to pre connection.