71 I think-Leon Russell and the Shelter People at the Atlanta Municipal auditorium. Leon was in his stride,awe inspiring.
For me, there's a number of them. Jethro Tull in 1973 in Montreal (the old forum) and Toronto (maple leaf gardens)-they were touring the Passion Play and it was my first show in a big barn. Pink Floyd the following year in montreal outdoors at the old Autostad. Seeing Chilliwack in St. John's in around 70 or 71. Lately it's been any time I see Gov't Mule or Tool
Dunno about classic rock but my favorite concerts have been Amon Amarth in 2011 Behemoth in 2011 Motörhead in 2011 Insane Clown Posse in 2013
I saw the Grateful Dead and the Allman Brothers quote a few times, dozens of times over the years. Tedeschi Trucks Band puts on a wonderful show, I’ve seen them a few times (and Derek Trucks is the nicest guy you could ever want to meet). To me nothing has ever topped the Black Crowes, though, especially from 1995-‘97. The 2005-‘09 period was also incredible. I’ve seen them close to 50 times over the years, and they are the best live band I’ve ever witnessed.