x2, put one probes on the male part and put the other probe on the outside outer ringto check for a signal on the RCAs with a DMM. all you do is set the DMM to a/c reading and play some music or test tones. it will give you an alternating readings while playing music, and a steady value while playing testones. if playing a test tone IMO to get an accurate reading you should play a 60Hz sine wave. since thats the freq that the dmm was designed to read most acurate. but all you really need to know is if there is a voltage swing on the rca's.