FWIW, I am having some 20' ICs to connect my preamp to my amp custom made for me as I type. Before I placed the order, however, I checked with the manufacturer of the preamp (McIntosh). I was told a run that length of RCA ICs would be no problem for my preamp, but that with some preamps, this can be an issue.
Make sure whatever you buy is well-shielded against RF interference.
Make sure whatever you buy is well-shielded against RF interference.