About two years ago, a buddy of mine gave me this old Realistic, four channel mixer, and I have never used it. I simply never had a need for it, but now, after picking up a set of 3 CM300's I am in the possible need to run a mixer. I know that there is a multi channel mixer that was made by Nakamichi, but I was wondering if anyone had any ideas on using this.
It's kinda neat in that it runs on a 9 volt battery (I have no idea how long a battery would last), it's pretty damn small ( 9"x4.5"x2.5") has 1/4' and RCA ins, and 2 1/4" out's.
The big thing I'm curious about is the ground connection

There's a little screw on the rear panel, but I have NO idea how I would ground this properly in the field?
I'm sure that I wouldn't want to run the Nak's into it without a ground, so please school me in some grounding principles and suggestion.

