Even though I’ve almost had to eat my words a time or two, I stand by my belief: rockers should rock as long as they want to rock. But I also believe that, when rockers pushing the age of 80 go out on tour, an aphorism of Robert Fripp’s may come in handy: expectation is a prison.

A perfect case study in both propositions cropped up this week, when my wife and I checked out our brand new downtown amphitheater for the first time. Headlining the night: veteran Canadian rockers Randy Bachman and Burton Cummings, out on tour as The Guess Who for the first time since legally reclaiming the band name from their erstwhile rhythm section. Opening the show: Don Felder, lead guitarist for The Eagles at their creative and commercial peak – though mired in contention almost from the beginning of his tenure and fired from the band 25 years ago. Each hit the stage with a different approach to their vintage catalog — and as the night unfolded, the differences told.

Felder, backed by REO Speedwagon alumnus Dave Amato on second guitar and Nashville pros Matt Bissonette (bass) and Seth Rausch (drums), hit the stage clean and pin-sharp, looking remarkably well-preserved for 78. “Already Gone” launched in a blaze of choirboy harmonies and a country-rock lope; “One of These Nights” shifted into a taut funk groove without the band breaking a sweat (no simple feat during an extreme heat advisory). The name-dropping Felder original “American Rock’n’Roll” kept up the onslaught — but cracks appeared in the music’s surface when, after introducing the band and paying tribute to his Southern roots, Felder sequed into the close-harmony ballad “Seven Bridges Road”. The backing vocals were obviously pre-recorded – no way could even four above-average singers sound that lush and resonant – and the instrumentals synced up uncannily with the narrative video playing on the back screen. From there on, I couldn’t help distinguishing the authentic from the assisted: noticing how newer tune “Hollywood Victim” recycled the nastier Eagles tropes about California girls gone wild; hearing how, when Felder’s singing crept up into Don Henley’s range, the grainy, robotic sound of AutoTune hung in the air. The final run of Eagles classics – “Take It Easy”, “Heartache Tonight”, “Life in the Fast Lane”, “Hotel California” – provided the thrills the crowd was looking for; plenty of rhythmic stomp from Bissonette and Rausch, Felder peeling off one stinging melodic lick after another, Amato channelling Joe Walsh when he locked in with Felder for double leads. But with all the genuine firepower onstage, the music was frequently as airbrushed as Felder’s vocals and his muscle car-styled logo. To be sure, the audience got what they wanted, and Felder did rock hard; still, I couldn’t help wondering how much grit was buried under multitracked layers of automated failsafes.

Ambling on to the prerecorded strains of “Hang On to Your Life” with their back-up quintet, Bachman and Cummings immediately established a loose vibe, kicking off with rootsy throwback “Runnin’ Back to Saskatoon” and b-side “Proper Stranger”. Immediately there were rough edges, but also a sense of genuine risk, as the rhythm section ebbed and flowed without reference to a click or a backing track. Still, there were downsides to The Guess Who letting it all hang out. At least on this night, Cummings’ high range came and went; though he’s the same age as Felder, he looked and sounded older, veering into Grandpa Simpson territory in his more nostalgic, showbiz song introductions. (To paraphrase one: “And when the morning sun comes through my windows and shines on those gold records, it’s sure a niiiice feeling …”) Thankfully, even though Cummings’ vocal flesh proved weak, his insistent, boogie-laced piano work plus the band’s sturdy playing powered through hit after hit, both from Bachman’s time in the band (mellow ballads “These Eyes” and “Laughing”, the chiming “No Time”, hard-rock smash “American Woman”) and afterwards (hippie hymns “Hand Me Down World” and encore “Share the Land”, retro-rockers “Albert Flasher” and “Star Baby”, novelty DJ tribute “Clap for the Wolfman”). And though the 82-year-old Bachman has been through enough wear and tear to stay seated for the entire show, he summoned up the spirit and drive to carry the night, his irresistible guitar hooks and raucous leads consistently pushing the group over the next rise. When Cummings stepped back for the Bachman-Turner Overdrive standards “Let It Ride”, “You Ain’t Seen Nothin’ Yet” and final encore “Taking Care of Business”, Bachman’s capacious bellow and funky, chunky riffs drove the crowd to their feet for the night’s biggest reactions, loudest singalongs and clapalongs, and longest, rowdiest ovations. By Keith Richard’s definition, if Felder rocked, The Guess Who rocked and rolled.

So, two different approaches: Felder reaching for perfection at the potential expense of excitement – which, to be fair, was how The Eagles typically went about their business; Bachman and Cummings being who they are, and letting precision go hang in search of the right feel. While I preferred The Guess Who’s sloppy yet spirited set to Felder’s machine-tooled entertainment, I can’t say one approach will always be better than the other. So, as acts rooted in the glory days of rock keep hitting the sheds this summer (and in summers to come), know your expectations — and be ready to break out of whatever prisons they’ve constructed for you, when the right band meets the right night. Either way, let rockers rock as long as they wanna rock!

The Guess Who’s “Takin’ It Back” tour with special guest Don Felder continues through August 22; US concert dates are here.

— Rick Krueger