Depends on what you're running. You could run a 6-channel and a 4 channel, or dual 5 channel amplifiers or, like you're thinking, dual 4 channels and a single mono block....You need to consider what you want out of your system. Running 3+ amplifiers will produce more power than 1 or 2 amplifiers could, however your cost will be tripled...read below.Stupid question.. If I have 10 speakers aren't I going to need like 3 amps? I channel per speaker right? (including sub) I have a chance to get a Pioneer 4 channel cheapbut I want to know what i should be looking at. I have the 10 speaker system and have ordered new door speakers and dash speakers. If I get this amp which ones do I hook up to it? Do I bridge?
You could also run your speakers at lower ohms which would convert your 10 speaker inputs into 5 inputs.
Remember you're going to need to consider everything else involved in running multiple amps, especially multiple-multiple channel amplifiers....extra rca's, bigger power wire, extra battery(s), grounds, etc etc etc. If you're going to run 3+ amplifiers you will need at MINIMUM 2 batteries (stinger/kenetic/etc), another alternator (possibly two more), 0/2 gauge wire...basically you're going to have to re-do almost all of your charging system.
Little more info is needed though....
How many speakers/subwoofers? How do you have 10 speakers mounted into your truck? 6 up front/2 in back/2 woofers...etc etc etc. What kind of power are you looking to run? Are you looking for glass breaking noise, or just a good solid loud system?