This amplifier is part of the new multi-channel system, designed for optimal performance for both 2 and multi-channel systems. The amplifiers use the new Electrocompaniet standard SPAC, (Serial Power Amp Control), to switch between multi-channel and 2 channel systems! The new Preamp (EC4.9), will automatically switch this amplifier into a 1×400 mono as soon as you play 2-channel music, and select this from the remote controller.