I know AVA's policy about not modding their equipment, but I am curious if owners have modded the rear connectors, internal wiring and IEC/Powercon plugs.
Newer AVA stuff all in new chassis has gold plated connectors. Older AVA equipment - e.g., based on Dynaco or Hafler Chassis - will not have gold plated connectors unless the purchaser specifically ordered same. If you think gold connectors make a better connection (and it certainly will in time as it does not corrode) then upgrading your connectors (if they are not already gold) may make a difference.
I don't quite see how replacing internal wiring will make a difference. And if you've looked inside an AVA unit, you'll see that the workmanship is beautiful.
I also don't see how replacing plugs will make a difference either. Assuming equipment has a properly designed and well constructed power supply (which is abundantly true of AVA stuff), I just don't see how anything prior to the power supply will make any difference unless it is defective.
If you have an early AVA unit and are itching to make improvements, Frank sells a number of kits. Also, for some of the early units there might be some small changes Frank's made in production runs that you could apply, e.g., better performing op amps, etc.