Details: 5F6-A running a JJ5U4GB, two JJ 6L6GCs, and all three preamp tubes. All done with build and double checking, setting the bias, and I'm getting some really puzzling voltage drop measurements from pin 8 of recto tube to pin 3 of 6L6. Basically, I'm getting milivolt values. Measurements: Resistance (Pin 3 of 6L6 to Pin 8 of 5U4): 59.4 ohms-outer, 54.5 ohms-inner Voltage Drop (Pin 3 of 6L6 to Pin 8 of 5U4): -0.324 volts-outer, -0.327 volts-inner Plate Voltage (Pin 3 of 6L6 to ground): 421 volts-outer,422 volts-inner B+ (first node): 429 V For what it's worth, it sounds great- Loud, dynamic. Ya know, like a Bassman. So if I move the decimal point of the voltage drop one decimal place to the right, I get a reasonable if a little too hot bias of 23 and 25 watts. Of course, I don't think there's any reason to do that. But math can be fun. Edited to add: I've measured with 3 different multimeters (including a fancy-pants Fluke) and keep getting these weird mV readings for the voltage drop.