Apologies if my non-user opinion is not invited, but my findings and opinion may be useful.
I've researched clean AC power a few years ago. I've come to the conclusion that battery power is the quietist source of AC power and that Stromtank was an established proven leader. However, battery power is expensive so a large enough unit is costly, so much so that the cost is usually better served with a significant component upgrade. For my situation, if I had the funds to buy a Stromtank large enough to handle my amps for hours OR sell my electronics then purchase my ideal end-game electronics, I'd choose the later. But price no object - Stromtank.
Dang, now you got me lusting for that lower noise floor. But the room has to be good enough to hear it. Double dang, I'm now lusting for a dedicated audio room - proper sized of course.