The stereo power amplifier SPA-4 and its big brother, mono power amplifier MPA-4, have been developed to present a holographic three dimensional soundstage where the listener can almost walk in and touch the musicians. Tremendous headroom is available in which to develop a wonderfully dynamic portrayal of music in all of its moods - ‘simply more music’. The stereo power amp has facilities for asymmetric (phono/RCA) or balanced inputs, the latter utilising a virtual transformer (discreet) balanced input circuit. The power amplifiers are symmetrical, current feedback, dc-coupled, gain stages with servo controlled dc off-set and multi emitter output devices. In the balanced mono amps the two power output stages of the stereo power amp are connected in balanced mode giving a mono amplifier. The mono amplifiers give single channel power twice that of the stereo amps. Among some of the gains of the balanced configuration is a much lower noise floor, even greater dynamics and a rock solid musical sound stage.