A simple modification to the stock N5X circuit is to add heater elevation. The idea is to reduce a small amount of 50/100Hz hum I was hearing with the power control above 5.
https://www.tristancollins.me/wp-content/uploads/2015/08/IMG_8006-scaled.jpg17072560TristanTristan2015-08-19 18:17:132015-08-24 12:34:29AmpMaker N5X Heater Elevation Mod