I am installing an Alpine CDA-9805 head unit along with their MRP-F240 4 channel amp and have no problems here. My question would be regarding the hook-up of a Sub woofer amp. To bridge this amp I would run 1 RCA out of the Head unit (left) RCA Sub Out....and then what?? It seems they want me to run it through the 4 Channel F240 amp some way for some reason. Can't I just run it to my Sub amp alone, bridged? Thanks in advance, Mike.