Eaton brand Pure Sinewave re-generators are all over eBay used. they will take the 120VAC 60hz from the generator, turn it into DC, and then back into perfectly regulated 120VAC at 60Hz.
they can also be used on your audio system, all day long, every day. that is what they are for. they are back up generators, industrial, commercial, bullet proof..designed to recreate the 120VAC all day long and switch to making it off a battery supply if the power goes out.
Thus they are perfect for multi use. For cleaning up emergency generator power and for cleaning up your regular AC coming from the power company, and for blackouts/flicker/etc via their own internal battery systems, which can be expanded. Or run off of battery-solar combos.