In simple terms Class A means the output devices (solid state or tubed) are kept switched "ON" regardless of audio signal input from the amp driver stage to the output stage. That is why Class A amps run "hotter" than Class A/B or Class B where the amp is really only drawing current when there is an audio signal passing thru the system. There are some good reference sources on the web, have a search on MSN under "Class A amplifier bias" and you should find something a bit more technical. Hope this helps, regards, Richard
