Each channel has 42 6AS7Gs, plus six other "support" tubes
The Atma-Sphere MA-3s put out 500 watts of Class A triode bliss into virtually any load. Each of the 3 banks of output tubes (14 6AS7G each) can be switched on or off to manage power and heat, the latter which is about 850 watts with all tubes on. 42 output tubes each. One stage of gain and no feedback. Built in power conditioning and can operate with no reduction in output power with as little as 95 volts in from the wall. Built in tube testing and automatic biasing, too.