I am involved in this exact thing and actually still in the middle of my testing. There are a few threads here that dance around the topic. Consensus that I have read seems like you should put your best cable from wall to P12, next best cable to source, then pre, then amp. Decided to test that on my own. My testing for cables usually takes me weeks, not an hour usually as differences are so minor usually. Like you, I assumed that my p12 was regenerating, so as long as it has current, it can be "junk" current going into it, as it will regenerate and make "good" current out the other end. I used the stock pc to run the regenerator for years, then used my high/better quality aftermarket cables to the components-decent consistent results. I recently picked up an aftermarket pc and threw it behind the p12(from the wall to the p12) what a difference! I was in the camp that cables don't make big changes for me, and I always look at them as minor EQ's at best, but this was the biggest difference I have ever experienced from a PC-and instantly.
Point is, the regenerator DOES benefit, in my case, from a good cable. I now have a new theory/analogy why this makes sense to me. As a car guy I always go to cars. May not help you if you are not a car person sorry! Never dawned on me before, but I wouldn't put a tiny carburetor and use low octane gas in a race car, and I believe this is similar. The engine can only make power based on what you give it even though it is just converting gasoline to power. A high flow carburetor(like the gauge of cable) and good race gas(the quality of cable) the high performing engine(the p12 and then the system) will certainly perform noticeably better. The car will reward you with good gas and a lot of it, just like the p12 when fed quality/ample power. The car will convert good gas into great performance, but it will in turn convert bad gas into only decent performance. In a normal sedan, lets say,(or like a mediocre system), the difference in gas may not be as noticeable-this only applies to a fairly resolving system, if that makes sense. Yes the p12 is regenerating, but WHAT it is regenerating makes a remarkable difference in my case.
Another thing to try is maybe try to run the panamax out of the output of the p12 and see what that does instead of out of the wall? I cannot speak for conditioners as I do not use them. I would like to think of them as fuel filters LOL. The fuel filter will likely not gain you any horsepower, but it can, if a poor design, choke your system. Only a silly theory of coarse. If you ask me about room treatments, I may go into body work analogies lol-I shouldn't drink so much coffee- hope that helps!