4 volts pre-outs are good. Get the most rms you can per channel if you plan on running the in car speakers on the head unit alone. If you plan to run a 4 channel amp, just the pre-outs are what is important.
im looking at a combo kit from sony. the deck has 17x4 rms and 52x4 max. 2 volt sub pre amp with seltable lpf/hpf. i dont know what that means.comes with two 190watt speakers. i could hook these to that amp. would that work good for a set up? thanks for all help