Everyone with a studio small or large should have one of these boxes. While simple, it is invaluable once you have one. The box I built here lets me plug in 6 guitar amplifiers and then 6 guitar speakers... and match any of the amps with any of the speakers by turning a couple knobs, no cable swaps needed. It also has a send and return to add a power attenuator/line out box with the ability to bypass.
Box is Hammond in Canada, aerospace grade wire, vintage knobs and Switchcraft jacks are all Made in USA.
Note the 2x6 position rotary switches. Each section is wired in parallel to combine the rated current. With these particular cheap rotaries, the power level is limited to 75 watt amps max. If you used heavier duty switches, you could easily up the power as everything else would be happy to hundreds of watts.