Why price of Tannoy speakers from online retailers in UK is cheaper than in US

VAT on exports to non-EU countries

VAT is a tax on goods used in the EU, so if goods are exported outside the EU, you do not charge VAT. You can zero rate the sale, as long as you get and keep evidence of the export, and comply with all other laws. You must also make sure the goods are exported, and you must get the evidence within 3 months from the time of sale. This can be longer for goods that need processing before export and for thoroughbred racehorses.
https://www.gov.uk/guidance/vat-exports-dispatches-and-supplying-goods-abroad#goods-dispatched-by-po...

I do not want to contradict  Elizabeth , but I would be supprised if the VAT was in the dealer’s price.
just on a marketing or sale standpoint, dealers of all sorts  try to attract customers by showing the minimum price.
Think about cars advertisement, the price that is published is far from the one that will be at the bottom of the bill.

I also like the walnut stain on these speakers.  I love to support local dealers but it is not justified for me to pay $4000-$5000 more for the same set of speakers. I agree that there are some risks involved in buying abroad.  If I am not ready to take those risks, I may need to explore other options such as different speakers or buy used ones.  

Regarding VAT, the online retailers do list price with VAT.  But as soon as I select country of destination (USA), It subtracts 20% from the listed price.  Also if I select some other products that they are not allow to sell, they will display "Sorry we are unable to ship this item to your area due to our agreement with the brand." 

Feedback from their internet site

John, Caroline du Nord

"I throughly enjoyed working with Nicolas. This was my first transaction in Canada. He went out of his way to communicate the CAD / US Dollar valulation plus border / custom fees.

I have No problem suggesting other American buyers to purchase through Nicolas in Canada .

Thank you Nicolas "

I want to underline that I have no interest in Son Ultime business.
I am not one of their customer .