Where can I have the amplifier voltage switched ?

It's not only a question of voltage. In Europe and I am quite sure in UK too, we have 50 Hz cycle. In USA in 60Hz.
This difference can create troubles to gears having motors for example.(possible lower speed in some type of turntable i.e.)
Try to contact the British distributor of your gears, they could possibly convert them.Some of them could have
an internal switch making your life easier.
In the worse scenario go to the PS web site, they have huge voltage/current transformers. But this will cost you !
Let us know how it develops

No sweat at all!
there are quite some threads in AudiogoN about this topic. You can change every unit to any voltage but basically the dealer/distributor/shop will charge you for that. (McIntosh charged me 250 Euros to change an MC2000 to 240 Volts f.e. which is ridiculous, of course, but I didn't want to have this baby suckle from any transformer).You also can use some step up transformer. There are galore in different electronical stores. So it depends if you want to change for ever or just for some time.
Good luck!

This question comes up all the time. Just search the archives for "240v" and you'll find all kinds of posts on this subject.

Mercury Magnetics does these kinds of job with ANY component you might ever think of at any specified time you'd ask. All their job is guarranteed.

It's probably the largest today's high quality transformer manufacturer and you'd find their customer service work immediate and excellent. I do not remember their on-line name but if you type their name on Google search box you'll immediately get their listing first.

Hi , I moved over from North America, and I had the same issue.
First the Company to contact is the Moth Group, Mike Harris he is the expert tel 01144- 1234 741 152. They make this Line Conditioners with step down transformers all built in one. They are very quite and efficient. Speakers no need for any change as they are not powered. Your CD player , Pre-amps, OK . I would change the Levinson Amp to 230V. Let let me tell you my HDTV 53" is working ,Pioneer DVD-37 all from 1 3000 watts transformer. The TV you will need a Multi VCR for the Pal to NTS , Samsung makes one and there are others, get it off e-bay. Any quetions just e-mail. Note Turntables maybe a problem but the CD Player and I have a Class A cdp not a problem with the 50-60hz stuff.