I want to hook my zone 3 pre outs to my garage receiver. I dont know long of run that will need to be but it will be pretty long. What is the best economical way to do this? Can I use coax with the right ends as RCA...can I get RCA on a roll and end it myself?

Side question...I should be able to listen to the same source using the main 5.1 speakers powered by the main amp...the zone 2 powered by the assignable amp...and the zone 3 powered by my garage receiver....all at the same time?? Amp is a Denon 4803...