SW1X Audio Design™ SPA V Zenith Performance Level 3/4/5 300B DHT Power Amplifier SPA V is a 3 gain stage Stereo Power Amplifier without input switch and volume control. Therefore it is ideally paired with our PRE III or PRE IV Line Pre-amplifier. The Directly Heated 300B Triodes at the output need no introduction. They … Continue reading SW1X SPA V Zenith Stereo Power Amplifier