Using battery power to go off the City's power grid

ricevs,

Here is an excerpt from your post of 8/5. 

"All inverters put out noise and distortion.....that is why they will all sound different from each other and will benefit from further (pure filtering) . The Stromtank and the Exeltech inverters are rated at less than 2% distortion....most of the others like the Giandel are rated at less than 3% distortion. This is not .0001 percent distortion like a Benchmark amp or Purifi amp measures. Distortion.....means noise.....I would think a larger inverter would sound better......probably lower output impedance and bigger power supply."

It's true you never said the Giandel 5000 sounds better than the 2000, but you said that a larger inverter would sound better due to lower output impedance and bigger power supply.  The safest thing to do is trust your friend's great results with the larger Giandel.  BTW, the Amperetime batteries can't be returned for a refund merely because you don't like the sound of them.  You have to take them to an approved technician who will document that there is a defect.

The Giandel 5000 plus 2 Amperetime batteries and cables is merely a $2800 experiment.  Well worth doing, thanks to your friend's experience.

NO ONE KNOWS ANYTHING. How many brands of power amp are there? They all sound different.....How many brands of inverters are there? They all sound different.

If "only" there was some way to "test" inverters in a consistent, repeatable manner and provide some sort of "scorecard" that indicated how well they performed their function 😎

Make your own batteries. Easy.

My equipment was not happy with a consistent 123-125V I was getting for years, transformers humming, can't be good for transformers. I finally built bucking transformer to be rid of the constant humming.

I did suffer both microwave oven and furnace motor failures during this period of high voltage. Since utility finally came in and fixed over voltage issue, no failures, no humming. I monitor my voltage 24/7, now between 119-121V, exactly 120V at least 90% of time.

120V is the standard voltage. 125 is not even really high. That would be pretty common if you are the near end of a line run. Transformer hum is not from high voltage, it is from DC offset and sometimes from wickedly bad THD on the line. Likely there was an issue with the mains transformer and/or balancing on your line between phases causing a DC offset. Consumer electronics company (and motor, etc.) will do extensive reliability testing with low voltage, high voltage, etc. as field failures are very costly and easily prevented. A large DC offset if a much different beast. With transformers and motors there is nothing you can really do.