Anyone know anything about audio monitors?

octatonic

Instead of a mixer try a monitor controller.

I have one of these:

but there are cheaper options available.

Snap

Tom, headphones- I use AKG 271 mk II. Closed back and v good,

chrispy108

I bought a cheap Behringer mixer to use with my monitors, works great. It was no more money than a "monitor matrix" type controller, but offers loads of flexiblity going forward if I need it for other tasks.