The Who’s show at Citizens Bank on Saturday happened almost 50 years to the day after the British Invasion band celebrated the release of Tommy across town in the cozier confines of the original Electric Factory at 22nd and Arch Streets.

In the half-century since, Pete Townshend and Roger Daltrey have most assuredly gotten old, despite their hopes expressed in “My Generation” in 1965. Their band mates Keith Moon and John Entwistle weren’t so lucky — dying in 1978 and 2002, respectively — but the twin front men have carried on in fits and starts, saying “never again,” more than once, but always coming back for more.

>> READ MORE: Roger Daltrey on ‘Tommy,’ The Who and saving Pete Townshend from sycophantitis

And thank goodness for that. Saturday’s holiday weekend performance in South Philadelphia served as a two-hour-plus reminder of the majesty and brute force of the band’s body of work and Townshend’s sui generis songwriting accomplishments. And if anything, it was more powerful and impressive for being unafraid to expose the imperfections that have inevitably revealed themselves with the passage of time.

The show opened with seven songs and 35 minutes of that 1969 deaf, dumb, and blind boy rock opera Tommy, the abridged version. Daltrey toured Townshend’s first magnum opus in its entirety just last year, and then as now, the rock opera was realized with the help of the Philadelphia Chamber Orchestra, featuring violinist Katie Jacoby and cellist Audrey Snyder.

That was a Daltrey solo show, however, and this was a full-on Who performance. So let’s just say that an engaged, gregarious, and at times downright goofy Townshend makes a world of difference.

Before the “Overture” was through, the 74-year-old guitarist had already whipped the crowd into a frenzy with trademark windmill power chords. And although the Who principals have never been besties — friction and Townshend’s vast insecurities have fueled their art — it did seem that the septuagenarians (Daltrey is 75) might actually like as well as need each other these days. (Speaking of seventysomethings, J. Geils Band’s Peter Wolf was terrific in a rousing R&B-infused opening set.)

The idea of two chummy Whos seemed plausible, anyway, from the grin on Townshend’s face when dodging Daltrey’s theatrically twirled microphone. Like, “Whoa, this is kind of fun!” And also from a two-song section alone together, with just Townshend’s manically strummed acoustic and Daltrey’s weathered voice, a little hoarse but strong enough.

They did “Tea & Theatre,” from 2006’s Endless Wire, the tune of most recent vintage in the 24-song set list and also “Won’t Get Fooled Again,” a warhorse effectively rearranged to encourage crowd participation and save Daltrey the strain of hitting notes he can’t reach anymore.

Townshend talked frankly of his own vocal limitations before “Eminence Front” — "I don’t know how my voice is going to be.” (The answer: Not great, but good enough.) And the band also had a couple of false starts, which Townshend teasingly blamed on Zak Starkey, the son of Ringo Starr, who’s a more effective Moon replacement than Kenney Jones was.

The generous-spirited set was creatively constructed. The rarely played “Imagine a Man,” from 1975’s Who By Numbers, made excellent use of the orchestra. “Behind Blue Eyes” was chamber rock, with the aid of Jacoby and Snyder. And the group’s explosive beginnings were nodded to with “Substitute” and “I Can See for Miles,” with the core four of Daltrey, Townshend, Starkey and bassist Jon Button.

The show built to a formidable climax with seven songs from 1973’s Quadrophenia, Townshend’s meisterwerk that made its case gracefully as the high point in orchestral rock history. He handled “Drown” on acoustic guitar by himself, and Daltrey came back with renewed vigor to bellow “Love, Reign O’er Me.”

But of course, there was another de rigueur number. It would not be a Who show without a stadium that was nearly full — thanks to deeply discounted last-minute tickets, going for as little as $10 on StubHub — of baby boomer rock fans shouting, “It’s only teenage wasteland!” on “Baba O’Riley.”

That communal catharsis was taken over the top with the aid of Jacoby, the Hockessin, Del., native and Philadelphia School of Rock graduate who took center stage for a showstopping violin solo while wearing a Bryce Harper jersey.

Townshend managed a little leap in the air as he came crashing down on the evening’s final chord. “This is the band," he exulted. "That is the orchestra. And this is Philadelphia!”