The 6215,623O and 6260 employ a continuous duty power supply section common to both channels. The 6290 has two totally independent power supplies with separate power switches and fusing. Reliable operation of these amplifiers is ensured through the following protection modes: Current is limited under improper load or drive conditions. Output relays, with front panel LED indication, protect the loudspeaker load under conditions of DC offset or large low-frequency transients.