Burning Amplifier Gain Stage Board which handles voltage gain for two channels when you populate it with your components. This board is required for both the single-ended BA-1 amp and the complementary BA-2 amp.
BAGS is the Burning Amplifier Gain Stage board. Being the Front-End, this is where all the signal voltage gain of a Burning Amp comes from. It's main purpose is to provide adequate gain to drive the suceeding output stage of a Burning Amp assembly.
Please visit the Burning Amplifier Helpdesk Thread for any questions you might have and for a definitive list of links to all articles and discussions about the Burning Amps.