The SPA-4 is a stereo version of the MPA-4 and uses the same class A circuit. The only differences are power output and the additional flexibility of both single ended and balanced inputs. Not every music lover can accommodate two substantial power amplifiers in their listen space, so a single SPA-4 could be the solution. One of the noticeable abilities of the SPA-4 is how well it works with smaller loudspeaker designs as well as large ones. Control and soundstage are two key elements of the SPA-4 making it a fine power amplifier.