So I want something that when hooked up to 4 speakers would reach the speakers own rms right? so if the speakers rms were 100 I want an amp like this amp?
Anyway I will be replacing all my speakers with alpine speakers soon enough (something like this maybe speakers), and would like to put 2 10"s maybe 2 12's in the back. So I now know I need that second amp for the speakers right? So are you saying I'm probably going to need a second amp for the subs??
Depending how many subs you are looking to install, you understand correctly like Buck said. Those 12's are 250 RMS for one. If you run 2 subs like that, that is a combined total of 500 watts RMS. So, in essence you want an amp that delivers 500 watts RMS, mono is the best considering if you wire the subs parallel to each other. I would suggest a Class D mono amp that matches fairly close to the subs TOTAL RMS. I would never run subs on a 4 channel amp though. It's not like you can't but I wouldn't recommend it. Have one amp strictly for your subs and the F250 for your components/door speakers. That's the amp I have as well and performs very nicely.