I think this would be a great amp for you (the MRP-F200): 1) It has four channels, for the four speakers that you currently want to power. 2) It is 75W x 4channels, and in the real world this is a lot more power than your Pioneer deck put out. 3) It has a pre-amp output on it, so it would be very simple down the road to daisy chain it to another amp if you purchase a sub. 4) If you can get it for $150, you're getting a great deal on it 5) Alpine counts as one of the quality manufacturers we recommended.

Again - from what I can gather, this is a perfect amp for you. I'd say thumbs-up.