North Coast Old Rasputin X

From their website:

Brewed in honor of the tenth anniversary of the introduction of Old Rasputin, this special limited bottling was released in January of 2007. Bottled in 500 ml. bottles with a cork and wire finish, Old Rasputin X was blended from beer aged for nine months in Bourbon barrels up to 12 years old.

Style: Barrel Aged
Color: Black
ABV: 11.6%
Bitterness: 75 IBUs

Bottle from a friend at a stout tasting.

Nose: Booze, vanilla, oak, dark bread, blackberries, toffee, caramel

Appearance: Medium brown, aged streaks of yellow near the meniscus, khaki/coffee w/cream head

Taste: Honey, oak, roast coffee, dark chocolate, booze, bread crust, wheatberries, apricot, wood, vanilla, plum + grape skin, toffee, caramel, hints of sherry.

Mouthfeel: Medium-thick, coating, long, lingering aftertaste and ever so slightly oxidized.

Thoughts: Superb dance between the caramel/toffee, the bitterness and the booze/oak. Spot on. Complex, sophisticated, yet quaffable. And above all -- delicious. Super delicious.

I'm curious as to where the extra booze came from? Old Rasputin is 8.9%. Did aging in the barrels evaporate some water? Did they change the Rasputin recipe? Or... did they blend in some Old Stock (me thinky!!!)

I usually find the concept of barrel aging to be more gimmicky than anything else. And the act of doing so rarely does more than oak up a perfectly nice beer. Or make it reek of vanilla. Not here. Old Rasputin X is not only one of the top 2 barrel aged beers I've ever had, but (probably) in my top 5 all time. Top 10 for certain.

Superlative.