Each of the three will also receive a year's free subscription to What Hi-Fi? Sound And Vision.
You'll need to be over 18, and available for the whole day next Thursday, 2nd of April. You will also need to organise your own transport to and from Teddington Studios, Middlesex, to arrive at our offices at 11am.
If you would like to be one of the three to take part, simply write an email with your full name, mobile telephone number and whathifi.com forums username, as well as your answer to the following question:
What size of TV was the Supertest in our April 2009 issue about?
Email to: thebigquestion@haymarket.com