The last time I placed an order at the Whisky Exchange, I added a bunch of rum samples for my wife and me to try.  She decided to pull out the Bumbu XO tonight.   There are several rum samples that I'm really looking forward to - a Rhum HSE finished in Highland Scotch casks, a Plantation 1998 Guyana Ocho finished, and a Diplomatico Batch Kettle.  But I expected the Bumbu to be sweet and simple - much more her thing than mine.    While it's fair to say that she liked it more than I did, it exceeded my expectations. Perhaps my surprise was due in part to the "Cask Type" description of "Oak Sherry".  I later discovered that the sherry cask was only part of the aging story - most of the aging was done in used bourbon barrels, and it really shows.  I picked up virtually no trace of the sherry on the nose or palate, but big notes of corn-heavy younger bourbon - vanilla, caramel, and butterscotch.   This is not the first bourbon barrel-aged rum I've had, but I'm certain I've never had one that has taken on bourbon characteristics to this degree. And despite the 40% ABV, it's acceptably rich and the alcohol is in balance.   Now for some perspective, lest I sound overly laudatory.  The XO is very sweet and not particularly complex, and would not be something I'd choose over the many rums that offer more depth and complexity.  Notwithstanding the bourbon notes, I'm sure that most of my whiskey compadres here on Distiller would agree.  But it's a respectable dram, and I'll pick up a bottle for my wife the next time I hit Total Wine.  When I do, I won't feel a need to shield it with a bottle of Lagavulin as I walk to the register.