POLL About Voltage Change on Audio Equipment

For gear that has dual voltage transformers, the alteration requires the re-setting of 4 wires which are usually under screws. Super simple, zero effect to retail value.

Low cost, reliable, high benefit, and now you can use US surge protectors on it. Totally the right way to go.

If this would require a transformer swap, it's usually prohibitively expensive and cumbersome to do, with some risk.  That I would leave alone.

@erik_squires makes a good point. There is some equipment on the market that is built with dual-voltage transformers and can be easily adjusted for use in either the US or Europe.  (Further clarification, none of these comments apply to equipment -- like your cell phone for example, that uses a digital power supply that automatically adjusts to whatever voltage it's plugged in to.)

However, my original comment applies to equipment that was manufactured with a transformer that only accepts one mains voltage.

The OP's original post did not disclose the make & model of the power amp involved so there is no way to offer any comment as to which category this amp falls in.

Anything that plugs into a wall has to have safety information on the back panel. If the unit has, for example, a multiple primary transformer that can accommodate different voltages, then all those voltages will be printed and clearly visible. Usually it's in the form of a list with blank boxes and the unit voltage has a mark on the corresponding box. This is the only way to be sure it's convertible without reconfiguring.

If a tech claims to have experience converting operating voltages on that particular unit -- and the unit only has one voltage printed on the back -- you'll have to use your judgment.