audio display board

hi everyone,

I am building my own audio board display and im racking my brain to work out how it needs to be wired up.

What I have made is a board with cutouts for 5 head units and 3 set of speakers and I would really like to build this up without have to buy and pre made boards, power supplies etc.

I already have a mains to 13.8 volts @ max of 30 amps so this should be enough to take care of the power to the units, but i would like to be able to do is to have 5 switches to switch on the head units, and 3 switches to change the speakers over, so that each head unit is able to run any of the speakers, but allow the customer to chose which headunit and which set of speakers to hear?

Does any one out there have the time to maybe draw something up for me or talk me through it, cause i think i have been trying to make it to difficult and confused myself!!

thanks a lot in advance everyone

Craig