This thread should be in the Liquor forum but too late now to change it.
The PX was a "duty free" only release until recently when they opened it up to some of the other markets. It is similar to Lasanta in that it uses sherry casks but these are far different then the normal sherry casks. The sherry barrels used for the final aging are Pedro Ximenez barrels a very sweet and rich sherry. They are custom made for Dr. Bill Lumsden (Head of Distilling and Whisky Creation) and are not simply used PX barrels. Dr. Lumsden has Spanish oak barrels made and then toasted on the inside. He then requests that they be filled with PX sherry for one year so that the charred wood soaks up all the flavor. Rumor has it that this malt stays in the sherry casks for two years after a ten year sleep in bourbon casks although if true I don't know why they don't have an age statement on it. Still, even at $65-75 it is a pretty good dram and that's the whole point isn't it?