the amp i have has RCA and high inputs what is the high input connection for

They are to be used when your head unit doesn't have a line level (RCA) output. What you do instead, is get the connector for the 'high level input' and splice into the wiring that goes to either front or rear speakers The amp then uses that as the signal.

Best to use the RCA inputs though if you can. Gives you more control over the amp from the head unit for a start.

thanks mate was just wondering what it was for, and now i know