SW1X Audio Design™ LPU IV Performance Level 4 6F6 Valve Phono Pre-Amplifier   In addition to Signal Output Transfomer (OPT) de-coupled Balanced design as employed in the LPU III, the circuit design of the LPU IV Phono is basen upon larger octal base valves. Instead of 2 gain stages of the LPU I, II and … Continue reading SW1X LPU IV Phono Pre-Amplifier