From what I can tell from the first post, the OP wants a box that has XLR ins and outs that can be turned on or off. No merging, phantom, anything else. It's a very simple circuit. For each xlr I/O simply put a switch across pins 2 and 3 that will null + and - (hot and cold) when in the 'MUTE' position and do nothing when in the 'UNMUTE' position. If phantom is running through it there will definitely be a loud pop on each throw of the switch. Easy to make, even with a short cable, not even an enclosure.

 

It could be a few bucks more, but you can find components for cheap from china. Tayda is a good place that ive been buying from for years. You just have to wait a couple weeks for shipping. It also doesnt have to be ugly! I guess if you are inexperienced or not very crafty it could be a chore and end up looking bad. I think its still worth doing though. My favorite filter is a piece of shit filter that is one of the first things i built years ago. It looks like shit, but it sounds amazing, and I built it, which makes me love it even more. But, i do understand your point, its sometimes easier to just buy a unit.

 

By mixing or switching?
If it's mixing two inputs I guess the cheapest option is hat thing:
https://www.thomann.co.uk/behringer_umc404hd.htm

I use the version with 8 inputs, you can sum up it's inputs for monitoring.
//Edit:// you don't have to use it as audio interface, it does that standalone.
These come up to 8 inputs
https://www.thomann.co.uk/behringer_umc1820.htm
But check how they treat inputs. Par and unpar to left and right. Yamahas / Steinberg's UR(I) interfaces do the same, but fancy with a mixer app.

 

Last edited: Mar 16, 2026