Generally, you can't use American electrical appliances in the UK (unless you buy an expensive transformer). The US electrical system supplies 120V at 60HZ whereas the UK system operates at 230V with a frequency of 50Hz. So plugging an American appliance into a UK socket will frequently result in damage to the appliance.
However, I note that the manual for the Bose SoundDock states that it operates at 100-240V at 50-60Hz:
http://www.bose.co.uk/GB/Images/AM286702_01-So undDock_ENGvo_tcm6-4096.pdf
This suggests that, apart from having to change the plug (or using a socket adapter), there should be no problem in using a US-purchased product in the UK.
For a definitive answer, I suggest e-mailing Bose. Click on 'Contact Us', for an online form, here:
http://www.bose.co.uk/GB/en/index.jsp
Remember that you'll have to pay duty and VAT on your purchase if the total value of all of your purchases, brought back from the USA, exceeds �145:
http://customs.hmrc.gov.uk/channelsPortalWebAp p/channelsPortalWebApp.portal?_nfpb=true&_page Label=pageTravel_ShowContent&id=HMCE_PROD_0102 20&propertyType=document
Chris