Can we replace the Stock amplifier that powers the 9 speakers?
I'm planning on buying a 6channel amp. How would you power the 9 speakers using a 6channle amp?
The 6channel amp is ~45watts per channel so it won't blow the OEM 9 speakers on the TOURING trim.
Possibly, it really depends on how the head-unit outputs to which channels. Obviously the center speaker gets one channel. Question being does the factory system use a crossover for the fronts (mid-range and tweeter). If yes, than 2 channels front, left/right. The rears are probably a co-axial design, so 2 channels for the rear. One channel left over. Should work in theory, and allow you to turn down the gains of the center channel to help correct the sound staging issues, and over-powered center channel.
I haven't looked at the touring audio system enough to know if it's 2 separate sets of rears (doors/ rear deck-lid for example.).
If you are going this route, I would definitely look into a DSP.