The 4.0 answer would be a power regenerator that is fed by 240 and puts out 120.
I'm not aware of one. i don't know why PSA and others to provide this. I looked for one to power a 240V amp from 120 and even called PSA and they weren't interested in even talking about it.
If you can't find this, then buy an oversized transformer--2000 to 5000 watts. Even an inexpensive transformer will provide power at least as clean at the wall. The downside is that your transformer may humm. If you can put the transformer in a room behind your stereo and poke a hole in the wall for a cable that would be ideal.
Jerry