This is from a point to point amp that I did not build. It is very quiet, very low hum of any kind. The heater wires from the transformer to the first tube are not tight wound, but they are not close to any other components. I have included a drawing of how the preamp and power tubes are connected. This is very different from what I have been doing. Basically I have been following how Leo Fender and many on this forum do, two tightly twisted wires going from tube to tube in series. The way this is done in the drawing looks simpler, any downside of this. Why is this not common in amps I see on this forum. Does this style produces “elevated “ heater. I have come across this style in some older P to P amps/radios that I have bought to salvage parts from so I assume this is old school which seems to have been abandoned, implying something wrong with it. Or maybe it was just forgotten over time. Any opinions would be appreciated Cheers Ron.