Should have the ability to adjust each channel seperately, but I don't think he needs a crossover... or does he?

He shouldn't need a crossover just for the factory speakers and no sub. But even in his price range, almost all new amps in that range will have crossovers built-in anyway, you just won't be using them. You won't need to adjust each channel separately, just adjust the levels of the fronts separately from the rears, and again, almost all new amps in that price rage will allow you to do this.

Looks like just about anything will do in his situation.