Re: Is an MRP-F300 amp enough to power 4 speakers and a sub?
No, it will not be able to power 2 sets of speakers and a sub very well at all - the salesman fed you bs. CAN it do it? Yes, but will it do it well? No.
It puts out about 150watts when bridged, so if you were to run 2 sets of speakers speakers and a sub, you'd basically have 2 speaker sets per channel on the first 2 channels, and one sub on the last 2 channels bridged. Since that amp puts out 75w per channel at 2 ohms, each individual speaker would be receiving about 30 watts - definitely not worth the effort of the installation, especially considering the fact that the sub will still only be getting 150watts. If you had your heart set on running a single amp, don't run more than one set of components. It wasn't intended to run 4channels plus a sub - only 2 plus a sub at most. And considering you like to listen to your music loud, you'll most likely clip the hell out of your amp if you tried to run 2 sets of speakers and a sub off of a 50w x 4 amp.
Just pick up an MRP-M500 used off the forums or craigslist. I picked one up a while ago for my sisters car for only $75 bucks off of craigslist (don't pay more than $80). There are a lot of other options as well that I'd consider a better value, if you don't mind your amps not matching.
Bought from: BassAddictJ, TBH1, Whitedragon551, Parker G, Ciaonzo, James Bang, GetLikeMe, Here-I-Come
Sold to: Slim2fattycake, Bigbangtheory, Safe_Cracker, Burton6431