Tegan and Sara perform 03Oct at the Burton Cummings theatre. (Brian Donogh, SUN)

If you went to last night's Tegan and Sara concert hoping to score a T-shirt with the twin sisters' likeness, there's a good chance you went home empty-handed.

From the time the doors opened, to the moment the Calgary duo took to the stage, the lineup for merch stretched right around the lobby of The Burt, and even up the stairwell leading to the first balcony.

That the Quin sisters inspire such slavish devotion in their fans is no surprise, given their act has always possessed massive cult cache, even when they were teen folk-punkers opening for Neil Young.

But if you thought last night's sold-out (and largely female) crowd looked even younger than the last time they here -- well, you weren't alone.

Maybe we can chalk it up to their new album The Con, the catchy alt-pop offering that accounted for much of last night's set list. The disc again finds the sisters growing as both performers and songwriters, but as with past albums, also proves they're stronger in the studio than on stage.

And so it was that last night's show was an entertaining -- but slightly uneven -- affair, one characterized by the spikier, more ominous sounds of The Con, with only the occasional ballad or poppier older track to provide levity.

Opening with a sparsely arranged Call It Off, the sisters slowly allowed the momentum to build, so when they arrived at Like O, Like H -- one of The Con's most adventurous tracks --Tegan's back-up vocals were 10 times more anguished than the album version.

Accompanied by spacey keyboard squiggles, sharp guitar blasts, and minimal percussion, they balanced older acoustic tracks like Divided and When I Get Up with newer cuts like the trip-hoppy Are You Ten Years Ago, and a radically reworked cover of Rhianna's Umbrella.

Their vocals were sometimes pitchy, but thankfully, their comedic bouts of between-song banter survived unscathed, as when Sara recalled how a muscleheaded lunk at one of her first shows had the gall to ask what an 18-year-old could possibly know about love.

"I was like, 'A lot, mother f---er,' " she deadpanned.

No argument there. And with observational -- not to mention songwriting -- skills that sharp, something tells us those merch lines are just gonna get longer and longer.