Thanks Robin. I got the transformers specced through Barry at Vyse Amps in the UK who just went on a weeks holiday yesterday so helpline closed for the time being… (I could contact the manufacturer if I need to but i’ll trust Barry).

I’ll take it that the impedance is as you suggest for the time being. The two thin wires are the primarys (red black), these correspond to the brown and blue in the diagrams? I was going to run the red to the positive of the far left filter cap where it joins with the 10K resistor and the black to pin 3 of V2, then the white to speaker jack negative and the yellow to positive. Is this right?

Thanks again!