I have a new Onkyo preamp with both xlr and RCA sub outputs. The cable run from the preamp to the Klipsch sup amp is 50 feet. I have a new premium RCA to RCA cable. After I bought it I discovered that the preamp has an xlr output. The sub amp is RCA input only.
Is there any benefit to sending the cable back to mono price in exchange for a XLR to RCA cable? If the sub amp had an xlr input I would for sure but in this case I don't know.
Try it with the RCA. If you experience ground loop noise the XLR out would cure it, but you would need a balanced to unbalanced converter at the sub end to use it. An XLR to RCA cable does not convert balanced to unbalanced, it just makes the entire connection unbalanced and won't stop ground loop noise.