I'm getting ready to set bias on my Fender Prosonic. I have read that generally you can measure plate voltage off of pin 3 (plate) and pin 8 (cathode). Any reason that won't work on a Prosonic? Schematic attached. I'm going to use a bias probe to measure plate current. By the way, the amp will operate in either class AB fixed bias or class A cathode bias, per a switch on the rear panel.