Would installing an aftermarket radio lose power in a VW monsoon sound system?

I have a 2001 VW Passat with the monsoon sound system. I have read that this sound system has an amp in the radio and installing an aftermarket head unit would take it out. So would this decrease the power to the speakers if I did this?Would installing an aftermarket radio lose power in a VW monsoon sound system?I used to be a car audio installer and found that installing aftermarket decks in cars with the monsoon system resulted in the system sounding overall worse. If you replaced EVERYTHING and added amps and sub you would have superior system, but the sound quality will take a hit if you only replace the head unit.