monsoon delco amp???
It is beneficial to use the monsoon amp with an aftermarket deck and speakers. It can be made (if wired appropriately) to sound much better than a deck amp, even good decks with 15-20 rms. Of course an aftermarket is better, but it still remains the monsoon amp is better than most head unit amps.
I've done it, and if you carry the bi-wiring appropriately to aftermarket speakers it will sound better than just a head unit amp. Most people either don't do the bi-wiring correctly, or would just rather spend the time and money on an aftermarket amp. Amps are so cheap I tend to recommend the same, but if you are simply replacing worn out speakers and a broken head unit, it can be made to sound rather good.



