Bose T1 ToneMatch Audio Engine Mixer & Power Supply (Bundle) This Bundle contains 2 items: Bose Audio Engine Mixer & ToneMatch Power Supply. The Power Supply is required when using the engine with an L1 Compact or L1 Model I system, or a Stand Alone Mixer or with a computer. Proprietary zEQ automatically adjusts the range of tone controls to match your voice or instrument, making it easier to fine tune your sound. Conventional mixers may have fixed EQ ranges that don't accurately affect desired frequencies when adjusted. Single-band ParaEQ centers on frequency you specify for each independent channel. Valuable tool for reshaping problematic frequencies in certain venues. Five reverb types (small, medium, large, plate and cavern) available for global assignment, with individual channel controls for decay time, mix level and brightness.