Cambridge Audio Azur 851W Class XD Flagship Power Amplifier in Black Two-channel power amplifier Class XD system, with 12 output transistors per channel CAP5 protection prevents against DC spikes, overheating, short circuits, and clipping Proprietary Terrapin impedance buffering modules separate amplifier and signal impedance for consistent sound across sources All-metal chassis provides massive structural rigidity, damping elements, and acoustic-resonance control