This video follows the routine service and overview of a 1960s Harman Kardon Commander Series DA-12 amplifier featuring a single-ended 6L6GC output and a 6CM8 triode/pentode preamp. The customer is using it as a harp amp, but it also makes a great guitar amp, as this video will hopefully show. In addition to the DA-12, Harman Kardon also made a DA-35 and a DA-100 in the Commander series.