Audiophile-Grade Amplification Eight channels of audiophile-grade Class D amplification, bridgeable and 4-ohm capable, featuring a unique ground loop/hum-free circuit design Eight Channels Of Audiophile-Grade Class D Amplification, Bridgeable And 4-Ohm Capable, Featuring A Unique Ground Loop/Hum-Free Circuit Design Four audio buses and included jumpers allow for wide variety of speaker configurations Four Audio Buses And Included Jumpers Allow For Wide Variety Of Speaker Configurations Specially designed for custom integration of whole home audio systems, the "AMP" serves as a companion amplifier for the Yamaha XDA-QS5400RK to expand speaker coverage and/or increase power output. It may also be used to expand secondary zone speaker coverage for Yamaha AV receivers that have Zone pre outs.