I found this concerning Laphroaig Scotch from their website:
It was not till the 30’s that the perfect barrel was found for Laphroaig. It was found to be ‘first fill’ bourbon, American oak casks. First fill only because this softens the wood to exactly the right depth, and bourbon because it’s a ‘sister Whisky’ and it does not impart a new flavour to Laphroaig. Subsequently 3 independent scientific papers from around the world have confirmed our choice. We already knew it 60 years ago – but that’s typical of Laphroaig.
And
However, we like to create a range of Laphroaig expressions to suit all tastes. As such, we use Sherry casks in our 25 and 27 year old bottlings. But perhaps our most famous barrels are the ‘Quarter Casks’.
These small, 19th Century style casks impart an intense flavour and are extensively used in our Quarter Cask expression.
Which leads me to believe that if you buy the 10 Year (what I have) you can avoid the sherry cask.