http://www.valvewizard.co.uk/se.html https://frank.pocnet.net/sheets/049/6/6AK6.pdf Merlin talks about finding the transformer load impedance. He uses the rule of thumb 'Z = Va^2 / Pa' Using 180V for the plate and 2.75W for the max dissipation gives a load of 11.78k. The datasheet recommends using 10k. Merlin's rule would result in 165V if using 10k. How much difference would there be? Merlin also says "the HT in a Class A amp must never be more than half the maximum peak anode voltage rating of the valve, given on the data sheet." The datasheet shows 300V max plate, 180V for class A. So, plate voltage could swing to 360V. Is this 300V for the bias point (not peak) or more of a suggestion? The 10k load with at 180V plate means plate voltage will max out at about 325V when biased at 98%. Maybe I just do that? @printer2 and @shortcircuit - I know you guys like 6ak6. What have you tried and gone with?