suburban battery dies daily

The radio probably is not what's killing the battery. They just don't draw that much power. Disconnect your battery overnight and see the battery is dying from an internal short. That's common when they get over four years old. Another thing is a "leaky" or shorted alternator which kills batteries overnight if battery is hooked up. Batteries and alternators can both be tested on the vehicle. Let us know what you find.

Sounds like they have everything that requires power running straight from battery. All of it needs to be ran thru the voltage regulator first