You won't find many if any high end amps with RCA connectors for speakers.
Radio Shack used to sell bare wires with male RCA's on one end. With these, if still available, you could run the bare wire out from an amp's speaker terminals and connect the male RCA on the other end to the existing RCA wire terminals, assuming these are female.
OR if you can, you can remove the existing RCA terminals and splice in wire extensions to reach the amp as you mention. IF you do this, be sure to keep track of wire polarity and run positive to positive and negative to negative.
Radio Shack used to sell bare wires with male RCA's on one end. With these, if still available, you could run the bare wire out from an amp's speaker terminals and connect the male RCA on the other end to the existing RCA wire terminals, assuming these are female.
OR if you can, you can remove the existing RCA terminals and splice in wire extensions to reach the amp as you mention. IF you do this, be sure to keep track of wire polarity and run positive to positive and negative to negative.