Can't leave you people alone for a moment. Definition of terms: "POC" is Piece of Crap, abbreviated. A tale of two (or more) transformers: I have a couple paperweights right next to my computer from back when I used to post on this topic nearly every day. One is a barbecued Schumacher 022772, the pre- '71 stock power transformer for Champ, Vibro Champ, Princeton and Princeton Reverb. Don't care what it puts out for voltage. Doesn't really matter. What matters is the available current which BTW is around 70 ma on the high voltage and 2 amps on the rectifier filament. (cue best boxing announcer voice) In this corner weighing in at a fraction of a pound or a pound and some fraction we have the Mercury Magnetics FBFPP shiny new and an exact copy of the stock POC. That makes it a POC as well in my book. Judging by the height of its core and the fact that it's supposed to be a replica of the stock PT I'd guess it performs exactly the same. It's all shiny new with wires dangling everywhere. I could do a comparo to the stock PT if I were so inclined. I'm not so inclined. The stock POC PT is barely adequate for a pair of 6V6s. Before repeating what I've said before, we'll take a peek at the tube data sheet. https://frank.pocnet.net/sheets/127/6/6V6.pdf First thing is says is max plate voltage 315v, max screen voltage 285v. We're exceeding that by a good 100v in a Princeton Reverb. Then we scroll down the page some. It says zero signal plate current 70ma, max signal plate current 92ma disregarding screen current. The stock PT makes around 70ma. That means when you whack it with a good hot signal the plate voltage is going to drop substantially. It has to make the current. There's ain't no such thing as a free lunch here. Clip an old analog VTVM into the B+ rail and watch it some time. Say it ain't so. Being as they copied the same old tube data sheet over and over there is no such thing as published ratings at the 420v- 450v supply seen in Princeton Reverbs. Doesn't really matter what the supply voltage is as long as it's somewhere between 300v and 400v as long as the available current is adequate. Next shiny paperweight we have is a Mercury Magnetics FBFFP-S, presumably fat stack, reduced voltage. This one is similar to the post- '71 Schumacher 10020, presumably around 100ma on the high voltage. I could tell you more if I could be bothered to hook it up. I'll state this as my opinion because I don't care to present a white paper to prove it: Dropping your supply voltage approximately 50v under the nominal stock and IMO way too high 420v will dramatically extend your tube life. If you want new reissue tubes to live reduced supply voltage is mandatory. "Better" is subjective. Dave is using a modified PI and admittedly his TP25 is one hefty chunk of iron. Dave also has Nashville leanings even though he's located way up on the northern Kentucky border rather than the southern border, closer to Nashville. To me a Sweet Spot looks a whole lot like a Princeton Reverb and it can easily be tweaked to sound and act a whole lot like a Princeton Reverb. If we assume the difference is just the transformers... it ain't. Short answer for those of you who like short answers: IMO we want 100ma minimum on out PR PT for cool operation and good tone. Anything over 325v-0-325v is too damn high and is going to cause problems with new production tubes. Ideally we want to see around 300v-0-300v and remember, 100ma minimum. We'll multiply that by our 1.15 fudge factor to estimate our supply voltage: 1.15 x 300 = 345. We might want to fudge our fudge factor to reflect actual reality. Multiply by 1.2 or 1.21. Starting with 300v-0-300v 100ma GZ34 rectifier we're probably looking at 365v. Don't make me come down here.