Noobmaker Needing help with Simple passive mixer design

Hello friends, i'm looking to making a simpler and cheaper version of the Jam hub https://www.amazon.ca/JamHub-GreenRoom-Silent-Rehearsal-Studio/dp/B002IJO3SG. My dream is to have a Jam with electronic instruments (particularly ipads with ableton link) in a library or a coffee shop.

I have a drawing of the unit that i'm looking to create. https://www.dropbox.com/s/imdrf1f1qhpmf77/IMG_0223.JPG?dl=0

the issue in question is creating this https://www.dropbox.com/s/pae18ikrw46cgjp/Screen%20Shot%202017-04-20%20at%205.12.13%20PM.png?dl=0
x 8
I would also need to add a headphone amplifier for each of the 8 sections. 

I'm having trouble trying to understand what parts i need to order. I'm guessing i need some dual logarithmic potentiometers in the circuit to adjust the input signal levels and some resistors to do the actual mixing.
could someone point me to the items on some website that i can go to my local Electronics store and order parts?

Why not just use a regular analog mixing device like a summing mixer?

The jamhub has horrible analog audio quality. I would not recommend trying to replicate it.

You want to be able to mix all your different instrument on stage? You need a line mixer. You can get a cheap one...which would be a resistive summing network like your 2nd schematic. Or a expensive one with inserts ect.

It is fairly straightforward to convert the passive mixer into an active one by adding a virtual earth amplifier. Something like a TL072 will do both left and right. I am nor quite sure how the rest connects together. You need to draw a  signal flow diagram to show what connects to what then we can advise you better.

Cheers

Ian

you need to make it active somewhere along the chain.
The Headphone amplifier will have to be active anyway.

Check this mixer, it would work for your needs:

http://www.generalguitargadgets.com/pdf/ggg_mixer_sc.pdf

http://www.generalguitargadgets.com/effects-projects/boosters/mini-mixer/