SW1X Audio Design™ MPA I Neptune Performance Level 2/3 6V6  Valve Push Pull Mono Power Amplifier   MPA I Neptune is a Pure Class A, Zero Negative Feedback, Fully Valve Rectified, Push Pull, 3 Gain Stage, Mono Power Amplifier. The powerful & grungy character of the triode connected 6V6G output tubes in combination with 6SJ7 … Continue reading SW1X MPA I “Neptune” PP Mono Power Amplifier