The cheap way to get more power from a tube amp is to raise the tube's plate and screen voltage, and bias them harder. It costs nothing to do so as a manufacturer, but we refuse to follow the pack. You will see claims of as high as 100 watts from a pair of KT120's. Initially, the customer is happy. But talk to the same customer in a year when his tubes are worn out. PrimaLuna amps are famous for long tube life, running cool, and being absolutely the easiest amplifier to own.
The best way to add power and keep running cool is an bigger build. We increased the size of the power transformer, added all the supporting circuitry including tube sockets, Swiss silver-plated OFC wiring, Takman resistors, SCR Tinfoil caps and a second Adaptive AutoBias board. And of course, four more EL34's for unrelenting power. And if you want the ultimate, add a second HP later and flip the switches to mono. Incredible!