I bought my Breuer in 1978 or thereabouts, corresponded with Herr Breuer, and acquired the 5C fluid damper (thus far unused) directly from him. After some carpentry was done on my SP-10 (a macassar ebony block to fill the opening where the previous owner had installed his own arm) I put a record on (von Dittersdorf string bass concerti) and called my then-girlfriend (now wife). After a bit of conversation, she asked if I'd gone and bought a new cartridge.
I asked why. She said "I know that record, and the string bass sounds 'stringier'."
Over the telephone. How's that for a testimonial?