My system is on all day for my wife's background music. The HVAC runs around the clock in summer (southern Nevada). One benefit of class D that people overlook is the much lower amp draw. I had an electrician look over my 500 watt class D system and he said it was nowhere near unsafe or needing any special wiring. We're on a solar net metering plan trying to go net zero.
We demand space, price, and energy efficiency from all our residential systems including audio. It is producer degree of difficulty, technology, simplicity. Our Yamaha NS-5000's are an example: 3.5 pound woofer coils with proprietary carbon fiber in all three drivers in a 600 watt studio monitor built and painted in a piano shop.