Why not use a 36 or 48 V battery and connect it directly to your amp's internal diode bridge rectifier, bypassing all troubles from 110/240V, inverters and what have you? It'll be a lot cleaner, and cheaper.
Using battery power to go off the City's power grid
I'm using a Bluetti AC200MAX 2,200 watt expandable power station to take my system off the city's power grid. It runs off a lithium ion phosphate battery with a 4,800 watt pure sine wave inverter. My total system only takes about 450 watts so I have never heard the fan kick on - it is totally silent. The music comes from a completely black background, with a huge soundstage that sounds very natural. I know that Ric Schultz has talked about these types of setups and there is a very expensive Stromtank battery system that is marketed to audiophiles. Anyone else tried this type of setup in their audio system?
Here is a link to a review: