Without getting too expensive, probably the best "bulk" cable you can get is the Mogami W2549. Obviously, you have to get one for "left" and one for "right".
https://www.performanceaudio.com/mogami-w2549-black-long-run-mic-cable-by-the-foot.htmlThere is another cable option - the Mogami W2534. It’s a quad-conductor cable, so you can do left/right channels in one cable and save drilling extra holes. It’s not as good as the above and uses smaller conductors. You would have to have a continuity tester to make sure you solder the correct conductors onto an RCA plug. There are two blue and two clear conductors internally.
https://www.sweetwater.com/store/detail/GoldMic--mogami-w2534-bulk-microphone-wire-priced-per-footfor RCA plugs, I think the best value for the money are the Cardas SRCA Signature. They are made from copper alloy and plated with rhodium over silver. It’s like a poor man’s version of a Furutech Rhodium connector.
http://www.soniccraft.com/product_info.php/cardas-srca-signature-series-rca-p-1474Soldering is always best for terminating RCA cables. Hope this helps.