Having scanned most of this thread, it’s always a good idea to run an aftermarket head unit, aftermarket speakers and a sub. If the internal amp in the head unit is in good working order, you should be fine, but that sounds iffy due to above descriptions. 22W continuous is sufficient power, no external amp needed to push the four speakers in the stock locations.
How did you hook up the sub? Did you use the RCA’s or an inline converter? If you have some pre-out RCA’s you definitely want to use those. That will enable you to control the bass signal to the sub separate from the other speakers.
At any rate, make sure the head unit is working properly, get the Polks from and rear and then just make your adjustments to your bass, treble, fade, etc...and you should be good to go.
How did you hook up the sub? Did you use the RCA’s or an inline converter? If you have some pre-out RCA’s you definitely want to use those. That will enable you to control the bass signal to the sub separate from the other speakers.
At any rate, make sure the head unit is working properly, get the Polks from and rear and then just make your adjustments to your bass, treble, fade, etc...and you should be good to go.