+1 on MAKING ABSOLUTELY SURE that the Belkin does NOT have any filter elements IN SERIES with the load. Parallel (shunt filter) elements are OK... but anything in-line with the output outlets, is ASKING FOR TROUBLE with a high-power amplifier.
I've lost count of the PA amps I've seen burnt to a crisp, from low voltage due to being plugged into so-called "power conditioners". The switching power supplies in many new amps just simply will self-destruct, trying desperately to maintain rated output, when the line voltage starts browning-out, due to the impedance of series filters inside these conditioners.
Other than that, the outlets themselves should not be a problem, as long as the TOTAL load on the Belkin is 20 amps or less. If the amp PLUS other things used through the Belkin add up to close to or more than 20 amps, then you need a separate circuit for the amplifier.
Regards,
Gordon.