12 speaker specs?

Hi

I’ve got a 2009 Yeti Elegance. It has the 12 speaker system with amp under the passenger seat.

the system as a whole is very treble heavy even with treble and mid turned down. There is loads of vibration/distortion from the bass speakers as well.

What I need to know is, 

A. What output (W) does the amp put out? I may upgrade the speakers with matching Wattage speakers

B. Is there a replacement amp that will plug into existing cabling? I am happy to do all aftermarket amp wiring, but would prefer a plug and play solution if possible.

C. Is there any simple fixes to the current set up so I don’t have to replace anything ( and save some money)

thanks in advance

Dunk