The M-Patch 2.1 from SM Pro Audio is a passive volume control/switcher that is designed for monitoring setups that employ a subwoofer. The unit performs a variety of volume control, level-matching, mixing and monitoring functions, all without adding any coloration or noise due to its 100% passive circuitry.
The controller features the ability to return the signal from the subwoofer back into the M-Patch 2.1 and control its volume along with the left/right monitors, all with the master volume control. Dedicated mute switches make it easy to A/B mixes with and without the subwoofer.
The main volume control is constructed with discrete 0.5% resistors using a switched mechanism that is far more accurate than using variable resistors, especially at low volumes. The chassis is suitable for either desktop use, or can be rack mounted using the included rack ears.
Note: Power is only required for powering the headphone amplifier and illuminating the LEDs. All other functions are available without the power supply connected.