Blackstar S1 50 Valve HeadThe ultimate pro 2 channel head! By switching both preamplifier and power amplifier parameters the Series One 50W delivers both Class A style tones with a bell like ring and classic push pull crunch depending on the mode selected. The ISF control removes the limitations of traditional designs allowing you to tune the tone to exactly the sound you are looking for. DPR can reduce the power down to 5W and MIDI switching and a series effects loop make