so, the amount of speakers i have is getting out of hand. So the plan is to hook everything up to a mixer and drive a single pair of speakers.

Can someone recommend a simple to use 16 channel mixer (for 8 retro systems in stereo) ? I really don't need anything fancy, just need to be able to adjust volume up or down. I'm looking at local used ones and the big mackie/behringer ones are just a bit daunting for me. too many knobs!