The 3:1 Mixer has two section of 3 inputs to a single output. Each input will be mixed at 1/3 of the level of the input. Each section has an LED indicator indicating activity on the output. Section 1 is normalled to section 2 so it can easily behave as a 6:1 mixer as well.

There is a jumper on the back to select between 1/1 (unity) or 1/3 (third) mixing for each channel. Unity will work better CV, while 1/3 will work better for audio.

https://afterlateraudio.com/products/3-1-mixer-1u