Equipment Repair

If BAT amp functions well, it does not need tweaking or upgrades. It's perfect as-is. If not than it needs repair with original components.
Tweaking or upgrading BAT will simply be a waste of money and devalue component.

Dead wrong, czarivey.  I have over a dozen mods in my VK75SE, one even recommended by Victor.  I've been in touch with many Agoners who have taken this path with BAT amps and preamps-- none were dissatisfied.  No commercial design is engraved on tablets of marble. 

I concur w/ dgarretson!