Mackie Mixer Mixer Unity Gain Combiner

From Mackie's site ( PDF owners manual)

We call it the "mixer mixer" because that's what it does...it mixes the outputs from up to three mixers so you can use them as thought they were one big mixer.

   Combing the outputs of two or more mixers has always been a difficult task. At best you could combine main outputs by givingup two outputs on one of the mixers. However none of the AUX sends or headphone monitoring functions could be combined.

  The mixer mixer solves this problem, combing All outputs from up to three mixers and providing a new set of outputs for up to three mixers. For example, three Mackie cr-1604's and a mixer mixer gives you 48 line inputs, 18 mic inputs, 12 stereo effect returns, and 24 direct outs.

  Since all combining is at unity gain, you lose no level or headroom- and gain no additional noise. In fact, the mixer mixer noise level is so low that you can use it at -10db or +4db levels.