• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Gemtune APPJPA0901A updates

I have been looking at the APPJPA0901A amp to power a pair of vintage Coral speakers for my office.

I have scoured the net but have not come across any sites that can tell me what, if any, upgrades have been made to the amplifier through the years?

The amp looks pretty much the same from the 2000s when it was introduced.

Secondly, have any owners updated their amps to make a noticeable improvement in SQ?

Tia