Not cask strength. :-) It was ordinary single-malt whisky, but non-chill-filtered. In chill filtering the distiller, well, chills the whisky and runs it through a second filtering; this removes lipids that will precipitate and "cloud" the whisky if it's iced, but which also contribute several layers of flavor and texture.

The string quartet was Cascade Strings, whose members' day job is with the symphony.

And, thank you.