Came across this link http://www.upsforless.com/liegxt22000rt.aspx for AC>DC>AC power regenerator/UPS (one of several similar units at the site).
Made for electronic/hospital equipment, but not specifically for audio. Does put out sine wave AC.
Is this suitable for hi-fidelity equipment? Is so, it's a good deal, as similar devices designed specifically for audio equipment are about double the price.
If it's not suitable, can you tell me why not? I'd like to understand the issue a bit.