I'm guessing it was Sunn O))). They did show a band member right when the song came on. Sounds like them
As for High on Fire. They just released their N American headlining tour dates. If you get the chance GO SEE THEM!!!!!!!!
November 26 - Toronto, ON - Opera House
November 30 - New York, NY - Bowery Ballroom
December 6 - St. Louis, MO - Firebird
December 10 - Kansas City, MO - The Riot Room