Can you use RCA slplitters to make 3 RCA out 1 RCA in?

If you only have one full range output on your radio, you can split the signal with y cables and make it work. it will divide the signal output voltage from the radio, between the 5 channel inputs to the amp. you wont lose power bc you can turn up the gains on the amp to compensate, but that will cause more hiss through your mids and highs. I would recommend finding a better radio with F/R/SUB RCA outputs and you will probably be happier in the long run.