Assuming a very comfortable load on the P5, would there be any advantage of the P5 and Power Base combo compared to just a P10 alone?
The P10 will beat even this combo. It’s noticeably better sounding than the P5 - which is not to denigrate the P5 in any way since it too is so good. The PowerBase will help from vibrations and airborne problems from speakers, but the added AC filtration buys you little if you have a Power Plant.