Features: The two rack-space, JBL 6670A is an all solid-state power amplifier capable of delivering up to 600 watts per channel into 4 Ohms with both channels driven, with independent protection circuitry on each channel. It has a switching power supply, and is available in one 110/120 Volt version. A choice of optional signal processing boards may be installed to provide either a Peak Compressor with High Pass Filter or an Electronic Crossover for Bi-amp operation. Parallel XLR and V*" phone connectors feed fully active bridging differentially balanced circuitry. A rear- panel switch selects between three modes of operation: Stereo, Dual Mono (single input to both channels) and Bridge Mono output. Neutrik Speakon® connectors supply Left, Right and Auxiliary (Stereo, Bridge or Bi-amp) speaker outputs. The chassis has both front and rear rack mounting brackets. Dual variable-speed fans draw filtered cooling air through rear vents, exhausting through front grilles.