Yes, the speakers will be fine, unless they are the active kind, with built-in amplifiers.
Some manufacturers make products with switchable voltage, and any of them should be able to advise on converting UK-spec products to run on US mains: should just be a case of a transformer change in many cases...
As far as I know, all the current Linn range (except the Majik turntable and Komponet 120 subwoofer) will work anywhere in the world without modification, as they use switch-mode power supplies instead of the more traditional transformer/rectifier/regulator design.