One Cord To Rule Them All

If your $5K "power regenerator" is going to regenerate the power anyway, and then you are going to run other power cords from the regenerator to the equipment you plug into it, then why not just use the largest gauge copper power cord that delivers current to the regenerator?  Your 9 awg Pangea AC-9 cord should be plenty large enough. I would be more worried about what is coming out of the wall.

I know some say it doesn't make any difference beyond a certain size but I have found otherwise after constructing power cords from 10 awg NOS WE wire and Furutech FI-11 connectors using 6 individual runs in a star-quad configuration - so an aggregate of 7 awg to each the load and neutral (and same to ground).  When run from dedicated 20A lines to my large monoblock amplifiers, the difference was a noticeable improvement over 10 awg Oyaide TUNAMI V2 power cables.  You can get basically the same cord from TRL as their Seven Plus - American Series, which is made from (you guessed it) pairs of NOS WE 10 awg wire.  I believe they braid rather than twist the wires (tomato-tomahto). 

What gives you the impression the P10 needs a "better" pc than the already better than stock pc?

Power cords don't "pass" wattage. 

Just my experience-I plugged a $25K+ Nordost Odin II into my PP which normally is a Heimdall II. No angels singing/rainbows. The PP just did what it  normally does. I also did Nordost Blue Heaven vs Heimdall vs Pangea AC13Se=no noticeable difference.  

koestner - can't say with certainty what will benefit your PSA regenerator.  Can say, I switched out the stock Istotek Premier on an Aquarius power conditioner for a Shunyata Venom HC and heard a significant improvement in sound.  I tried a Pangea AC9 on it but thought sound with the Venom HC was better.  I heard further improvement over the Venom HC when I tried a Shunyata Delta NR v1 and still more with a Shunyata Alpha NR v1.  The biggest step-change, however, was with the Venom HC.  Call The Cable Co. and you can rent a Venom HC or get in touch with Music Direct.  You can buy from MD with a long (45? or 60? day) money back return option.  Good luck.  Hope this helps.  

MC and TJ:
600 watts I think is about correct as the P10 says the system is drawing 420 watts at idle (my 2 mono amps idle at 150 watts each). Now the P10 runs at about 66% efficiency so 420/.66 = 636 watts. If it goes from the wall into the P10, then yes it is passing the watts through the cable. Watts are Voltage x Current and about 600 watts are passing through the power cord while my system is running.

I was thinking of going to a solid core cable instead of stranded, but keeping within my budget... any chance?

@koestner 

I highly recommend VH Audio Flavor4 cord for $335 / delivered. I doubt you can do any better than this cord in your price range. 
https://www.vhaudio.com/flavor4.html