SW1X Audio Design™ LPU I Performance Level 1 MM Valve Phono Pre-Amplifier   The phono pre-amplifier is based on a classic all valve circuit design used to master vinyl recordings and master tapes. It is a two gain stage design consisting of 2 (one for each channel) pentode valves on the input and one double … Continue reading SW1X LPU I Phono Pre-Amplifier