The Neutrik Rean RCA connectors are a breeze to work with, also on the Ultra, making a proper connection without excessive force.
My Cordial CFU CC rca cables which are made the way an RCA cable should with a single conductor plus shield, use those. They come in pairs in 0.6, 0.9, 1,5, 3 and 6 m lengths, black or white cables and connectors.
Thomann distribute world wide.