There are some "audiophile" UPS products such as THESE or THIS ONE . I cannot say how these work since I have not tried them out. The Panamax unit seems more reasonably priced for an audition, so I may give that a try in my system.
In any case none of the units I have seen look like they would work very well with power amps that draw a significant current so I would not feel good about plugging my amplifiers into them.