I am looking into building this stereo amplifier based on this circuit: 2 x 22 Amplifier
However, as I am pretty new to circuit building, I have a question about the ground lines: Do i tie all of the ground lines to the earth ground on the power supply? On the schematic, it shows +12v in, and out to "GND", and i am not sure if I should use the common ground line by itself as the end point, or if i should ground the common to earth. Any help would be great, and apologies if this is somewhat redundant, thanks!