Just a little update at my end, I dropped the 10k cathode resistor down to 4.7k. Don't like it as much at low volume but it sounds pretty good to my ears when the master gets cookin. (as do most amps or higher gain preamps)
Also moved the negative feedback tap from 8 ohm to the speaker jack and I quite like it. It is more subtle than I thought and to my ears, the "browning" of the tone is due to the fact that it smooths some of the highs and adds a bit of fullness. You guys notice this as well or is it my imagination?
I'm going to try a few bypass caps now to see what I like. I think I am also going to add a tonestack lift switch for a bit more plexi on 10 oomph alla Bogner Helios. (also has this feature from what I understand of the explanation of the amp)
I've left a 500pf bright cap in to date. I like the bit of extra crunch you get from not removing it but we'll see if it is too much once the bypass caps come in to play on V1 and V2.