Tamdhu distillery fully matures all of its single malt whisky in Oloroso sherry casks. That said, the wood type is definitely more important than the sherry type, if you want to predict the profile of the whisky.
For Quercus Alba Distinction they specifically selected white American oak casks. Compared to European oak (see Tamdhu Cigar Malt for instance), this should result in a softer oak influence with more vanilla roundness. The colour is also noticeably lighter, with less of the characteristic red-brown hues.
Tamdhu Quercus Alba Distinction (48%, OB 2021)
Nose: quite sweet, balancing spicy sherry (pepper, nutmeg) with oranges and vanilla. Some honey and fresh wood shavings underneath. Then also a refreshing minty side. A little apple crumble, candied ginger and cinnamon too. Maybe not what most people would expect from a sherry cask, but it does scream white oak.
Mouth: a fairly thick texture, with slightly more fruity notes now. Orchard fruits (apples, plums) with honey. Then also malty notes and a subtle hint of white grapes. Leathery notes appear, alongside ginger, almonds and white pepper. Subtle vanilla and cocoa in the end.
Finish: good length, with an oaky warmth of sherry spice and vanilla custard.
I’m not sure this offers a lighter oak influence, but it definitely revolves less around dried fruits. Instead you get a little more vanilla, candied ginger and sweetness. Good whisky but I prefer the darker bombs. Available from The Whisky Exchange or Master of Malt for instance. The second edition is also available in stores.