The versatile Little 40 L6 Tube Guitar Amp Head is the perfect amount of power for most live and studio situations, and the amp’s Continuous Power Control (CPC) allows you to get the tone you want at the volume you need. The amp automatically biases AND matches (if the tubes are within 20%) the output tubes. Change the tubes for different sounds and power. No more trips to your service tech for biasing. Continuous Power Control (CPC) This patent pending feature allows you to control the actual power of the amp, from full power 40W (class A/B) gradually down to 1W (class A) in Pentode mode—or 15W (class A/B) to 0.5W (class A) in Triode mode. BIAS Switch (low/high) The Little 40 can operate in either Low Bias mode or High Bias mode. When this button is pressed in, the power tubes work in High Bias mode; when the button is depressed, they work in Low Bias mode. In Low Bias mode, the tubes use less power and less ‘tube life’ is taken out of them. High Bias mode gives top quality and power, and higher-fidelity sound—but the power consumption and dissipation of the tubes increases. In either mode, unlike other tube amplifiers, the Little 40 is able to greatly prolong the life of its tubes by keeping them optimally biased at all times.