What are the models of the amps?
You can use 1 RCA from the HU and buy 2 Y rca connector splitter and use 1 for the 200 watts amp and another to the 1000 watt amp.
http://www.audiogear.com/Resources/~AdptRcaFto2RcaM
I just got a Boss Riot GT 980 5 Channel Amp. I want to use Channel 1&2 for my front speaker channel 3&4 for my rear speakers and Channel 5 for my Sub.
Amp has 3 RCA terminals but my radio only has 1. How can i do this?