I'd like to see the circuit when and if he publishes it.
Just noticed it also says it is run in Class A1, not Class A. Some tube gurus say the extra couple of watts gained from Class A1 is a backward step, rather a couple less watts and pure class A. I don't know never compared the two. It's getting good press and got all us talking about it.
I built a copy of the SET DHT Wavac MD805m mono blocks once no expense spared for transformers, complete with 300b driver and interstage transformers to the 805 RCA tube, the better I tweaked the circuit for sound, the closer I got to to one of my Class A water cooled solid state amps, in the end I stuck with class A solid state.
Cheers George