GROUNDZERO 2 channel pure SQ amplifier - 2 x 420 WRMS @4 ohmGround Zero GZPA REFERENCE 2PURE 2 channel Class A B SQ Amplifier 2700 Watts Max Reference High End Amplifiers Only the Best components ever have been considered good enough to find the way to the GROUND ZERO REFERENCE Amplifier line up. Each model offers adjustable BIAS control, Setting the operating mode from class A B very close to pure class A. Apart from that, All models feature wide band filters and bypass function additionally. Massive and