changing from 220v to 120v


There are a pair of Bryston monoblocks I am interested in that are 220v. The dealer says he can change them to 120v before shipping. I know next to nothing about electricity. Is the conversion easy to do correctly and well? Or migth there be non-trivial issues involved?

thanks for your thoughts.
tanglewood
Depending on the gear, yes. With linear power supplies we often see transformers that are manufactured as dual voltage units. These transformers use two primary coils, and depending on whether the primaries are connected in series or in parallel to each other they work with 220 or 110.

It’s a common cost-saving technique.

Best,

Erik
Thanks for the response.  Do you know whether Bryston builds their amps for easy conversion?
Shouldn't be a problem. Cheers,
Spencer
Do you know whether Bryston builds their amps for easy conversion?
If the dealer is doing it, without sending it back to Bryston, then it’s easy.
"Could" even be an internal switch, or soldered bridging pads
Cheers George
I know nothing about the internals of Bryston, but it's often just spades on a terminal block.  Takes a phillips head screwdriver and voila. :)
Bryston probably knows.
+builder3, call Bryston.  While your at it, make sure with Bryston that there are no warranty issues if you do it yourself.
James Tanner, owner of Bryston, recommended not buying amps built for a different country. I am going to heed his advice.  I'm also worried the warranty might not transfer.

thanks for all the responses. 
I woulds never buy a 220v amp to be converted get 110v only it could be a problem.
it really depends on how a specific unit is built and whether it is internally configured with proper power transformers and circuitry to handle different input voltages - some are easy to do, made for quick-shift... others not so much

so i would lean on the manufacturer to advise on the wisdom of the input voltage swap