I have a P20 ( 15 amp ) running my gear:
Maggie 3.7i off a BHK 300 pair, PSA DS DAC, PSA DS transport, Preamp, VPI Classic 3, Oppo DVD.
2 JL Audio subs plugged into wall not P20.
I have the chance to either buy a used P20 or a new P15 for the same price. I was going to use the current P20 just for the amps, then whatever new unit to power the front end stuff. Would there be a noticeable difference in sound in the P20 or P15 if it’s powering the front end gear?
Probably not but for the same price why not get the P20? What is ‘used’ for a power plant…they either work or don’t not much to ‘wear’.
Another way to look at it is the P20 is proven.
Paul multiple time posted that the P20 sounds much better than the other ones, independent of the power demand.
I haven’t used a P15 but I feel the P20 will provide a bigger impact on sound quality. But, first I would recommend that you should install a dedicated 20 amp circuit and buy a very high quality 20 amp power cord. I was really shocked at the improvement in sound quality that the addition of my 20 amp power cord provided, after running my P20 on the 15 amp setting (for about 2 months, that was my comparison point).
Even with your power needy Maggies, I feel one P20 will do, especially with the 20 amp circuit. Consult with the PS Audio techs. (Also, I suspect the 20 amp circuit will add to your systems headroom).
Chas
At this time and location of equipment, a dedicated 20 line isn’t possible. But in the future it will be. I will add two. I am leaning towards a second P20
That is a fact. The P20, with its much larger power supply, storage, and greater number of output devices, is a significant step up to any of the other Power Plants. Not that they are slouches—they are not—but the P20 simply stands heads and shoulder better.
Thank you Paul for helping make up my mind. P20 it will be
Duh, P20. LOL
Paul, the higher power capacity and outlets to me seem not as a reason for better sound for just source components…wasn’t it the lower impedance?
Is the same sound quality not reachable with less power capacity?
I have more of a basic regenerator question, but seems somewhat related … is there a practical or suggested limit to how long a power cord can be used for components connected to a regenerator? I know there has been discussion on the loss of the “low impedance” power delivery when extension cords are used, but don’t recall a specific length being stated. Asking for a friend … 
For what it’s worth, I sold my P10 and bought a P20 (@pmotz bought my P10 a while ago). I have never been that convinced the P20 is that much better than the P10. Given the new pricing market for a P20, I would likely look for a good used P10 if I was new to the product category. Please keep in mind that I have not experimented much. I bought the P20 and use it. I haven’t tried a lot of A/B, with and without the P20.