TOA make a range of industrial PA amplifiers designed for schools and factories etc. I have a mono 60W version which is designed to run on both 12 Volts and mains power - the battery presumably being there to cope with failure of the main electricity supply.

They're heavy and rugged and clearly not meant for everyday vehicle use. I use mine coupled to a very large Yamaha monitor speaker for PA use when mains power is not available - I use a 12V deep cycle truck battery which I use with an electric outboard or for camp lighting at other times.

The quality and volume of sound is seriously good, particularly when compared to the general offerings for portable PA's for school use.

Best of all you can pick up TOA's and similar for a song at liquidation sales for restaurants and warehouses. (12 Volt ones aren't that common however). Don't be put off by the mass of terminals on the back of the amp that read 70V or 100 V outputs, just use the 4 ohm or 8 ohm speaker terminals.

I don't kmow whether TOA or others make stereo amps - stereo is probably not appropriate for permanently installed multi speaker premises.

Regards, John