I hate to complicate the discussion, but a well-known cable manufacturer once told me that RCA interconnects should generally not be shorter than 1 meter. He gave some kind of scientific explanation I didn't understand, and I can't guarantee it was simply because he didn't want to fool with selling anything shorter.There would be some truth in that in the case of a DIGITAL rca (or bnc or xlr) cable, where in fact the ideal length is 1.5 meters or slightly longer, as explained here.
However in the case of an analog interconnect the only reason that is conceivable to me that would make a longer length sonically preferable to a shorter length would be if the user wanted to introduce a coloration that is complementary to the colorations of the rest of the system.
Regards,
-- Al