I'd email Sarah or Steve to get the poop straight from the poopers. I understand completely, a seasoned amp is something special, a few years on these amps and they start to bloom and grow more refined and more musical still. Modding that core seems a great idea. I had beeswax caps put into a seasoned Torii and it was a great thing to do.

Matchman,

About the only thing you could do to improve that 12 watt push-pull is upgrade the output transformers to better bass output ones. That would mean a new chassis and probably would be tedious because if my mind serves me correctly, that amp uses a parallel combination of (2) each channel and they had to be matched by trial and error. Not bad when using the cheap ones Steve uses in their but expensive if wanting to run full output bass models. Sell it?  ::) Ya, sell it!