Hardware question

[Kevin Brown]

Computer related, but not really OS specific.

I have several systems in a room together and I'm looking for a way to 
integrate their sound outputs together with some external mixer device.

Basic idea requirements (minimum)
4 inputs (1/8" preferred to avoid signal loss from adapters)
2 outputs (again preferred to be 1/8" stereo jacks)

Each input and output needs its own volume slider so that I can kill an 
output by just pulling the slider all the way down (same with each 
input).  I don't care if it is a passive device (no power input) or an 
active one (AC input).

The purpose is that I want to be able to have all the systems hooked up 
to one set of speakers and a set of headphones without having to reach 
behind any of them to adjust jack connections and want to be able to 
have them all connected together since I have music or movies coming 
from any one of the systems as well as games.  It was suggested that 
Creative made something like this, but the few things I saw on their 
site seemed to require a sound card in the system for those boxes and 
were more for mixing audio sources (MIDI, keyboards, and other 
instruments).  I'd rather it had no dependancy on a card in a system or 
on any OS (e.g. no USB connections or software or drivers to control). 
This is because none of the systems are always up.

Thoughts?  Suggestions?  Links?