Eaton 9PX. I have had both the P20 and the Eaton in my listening room, all else equal the Eaton 9PX delivered to my ears the same experience. It also costs much less and uses double conversion. The only downside is you have to feel comfortable installing a quieter fan, the stock one is very noisy as it is meant to be used in data centers.
I am not the only one who has compared the Eaton 9PX vs P20: