I strongly recommend against using an uninterruptable power supply
in a home, at least if it has the same implications as what it does
at my workplace.

With a UPS, you can have a short-circuit and the power will continue to
flow.  On all of the machines here that are connected to a UPS, we have
a red button that shuts off the power in case of an emergency.  While
it should protect from spikes and power outages (I've yet to understand
why it would be a major concern on a player piano: live without it!),
it would make more sense to simply place a surge protector in line with
machines that you want to protect -- much cheaper, easily installed,
and inconspicuous.

I operate my 110-volt Ampico through a 220/110-volt transformer.
Yesterday the plug shorted out and it merely blew the circuit breaker
from the transformer to the piano: quick, painless, didn't damage
anything, perfect.

Eli Shahar