83 GMC amp (no sub, just speakers)

[Jeepwm69]

I have an 83 GMC C1500 that currently has an old Pioneer AM/FM/Cass in the dash that still works. Think it puts out something like 7.5RMS or something ridiculous like that. Hooked into factory speaker wires. I have 4" Pioneers from Walmart in the corners of the dash, and tried to wire Blaupunkt 3.5's installed in a plate in the center speaker hole but they are horribly distorted if I try to run all 4 front speakers off the front speaker leads, so the Blaupunkts are currently unhooked.

Have 6x9's in boxes behind the seat

Soooo, I'm not looking for bass thump or even really loud sound, just want clear music at a reasonable level.

I figure the best way to approach this is an amp. Hook front 4 speakers to the front 2 channels, rear speakers to the rear channels. That feasible?

I don't want to spend much. I see cheaper brands, Boss, Pyle, Pyramid etc. I'm not looking for audiophile sound here. I'd be content with factoryish sound. Will one of these sub-$50 amps do the job?

Anyone have any suggestions on what I should use, and any comment on how I plan on wiring it?

I'm honestly probably going to put the factory AM/FM radio back in at some point and hook up an FM modulated aux hookup so I can run my ipod, and I'm sure the factory radio is a low powered unit like the Pioneer I have in there now.