RNS has 4x20 watt amp.The Monsoon amp puts out 18W/ch into 4 ohms, and roughly twice that into 2 ohms. The two rear woofers are 2 ohms. So that's 18W * 6 + 36W * 2 = 180WPioneer would give better sound quality, but you would loose oem looking. Also, for external amp, you should buy extra cable for line- outs because Pioneer doesn't supply it with new HU. In my opinion, monsoon would work with Pioneer, but you would have to modify the cable.