I put together a quick test in my dev chassis of the 1st valve in the pre amp stage, mainly to test if the old Mullard and Mazda pulls in the junk box had any AF service life left in them.
All worked ok, I input a 200mV sine wave and got a nice clean 40V out and were flat (eyeballed only) up to 18kHz. All valves were within 10% of each other. Tried a couple of EF80s too.
Next I'll start a new thread to get help with the push pull section as I've already taken it way off topic
Doug.