Hey Doc - I bypassed the switch, only use one set of inputs.
Anyway - it was definitely the driver tube - I replaced it with a JJ ECC81 Gold Pin - Not a subtle difference, my bass is back in spades, I have more volume, everything sounds more defined.
i am guessing that driver tube was faulty from day one and was causing me to have less fidelity - This amp just keeps getting better and better.
Any chance you can send me a replacement tube, just so I have a spare?
thanks,
drew.