Hello everyone!

I own an Audi A4 B5 1,9tdi (85kW) 2000 ( sedan and facelift version),

My question is about the amplifier, how much wattage does it have?

I have 6 stock bose speakers in total, which are in the front door (4') I suppose that the rear door has the same (4') or even bigger? and the rear deck has (6.5'). ( Can you also tell me the wattage on those stock bose speakers?)

A couple of days ago I changed the front door and the rear deck speakers,

Front door - Pioneer TS-G1020F

Rear deck - Pioneer TS-G1730F

The main problem is that I and my friends have noticed, that the rear deck speakers have like kinda distorted bass and no sound coming from the tweeters, they are working perfectly fine, but I don't understand what makes that bass sound like those speakers are about to blow up, and almost can't hear any sound from tweeters. I usually had the bass setting on maximum, but now even when I change it to half and turn volume up it's making the bass kind of distorted, maybe the amplifier needs to be changed, I don't know, hope you guys have any answers for that.
Have a good day!