Oh wow 80 Lbs, well at least that makes me happy, it means the amp I’m building will be lighter by comparison at ~40 Lbs, maybe 45 Lbs due to the chokes, then again, maybe the 300Bs have Plate Chokes making them even heavier. Mine uses 6080s and equivalents with CCS on the plates of the drivers and on the power tube cathodes, making it substantially lighter, that and the transformer is toroidal and provides 150V only (when rectified it’ll be higher though) with the heater winding being 6.3V for all tubes. I’d imagine the 300Bs are being run with maybe 300V, or higher, and possibly more windings due to the transformer having to heat a 300B and the driver tubes, each at different voltages (Or a separate transformer for heaters and plate voltage).
Idk I thought I was going overboard at 40 Lbs.
Oh also, I’ve heard the Xduoo amp is purely tube, but idk, seems weird that it can produce 3000mw into a 32 ohm load using just 12AU7s. Maybe it’s internally balanced using phase splitters on the RCAs, and uses OT to take the balanced signal back to unbalanced, although it is rather small or maybe it has a particular biasing but idk.
Still I’m curious to see someone open this sucker up and see how it works.