On their 2009 album Sainthood, Tegan and Sara made some tentative steps into the pop mainstream by stripping their sound down to the bare essentials and delivering a batch of their hookiest songs to date.

Four years later, on 2013's Heartthrob, the duo dives into the pop mainstream headfirst.

Working mainly with producer Greg Kurstin, the duo's approach is slick and punchy with lots of synthesizers, programmed drums, and a sound that falls somewhere between Robyn and Katy Perry on the pop spectrum.

While longtime fans might be a bit perplexed by the shift, they will find plenty of familiar ground to cling to as the record plays and the smartly written and tear-filled songs follow one after another.

Indeed, the core musical values that have always made Tegan and Sara special, like their ability to write super-hooky melodies, their willingness to strip their emotions bare, and their powerful voices, remain fully intact on Heartthrob, and the shiny package that surrounds them only seems to have made their collective impact stronger.

The insistent impact of the album's opening track serves as a statement of intent -- "Closer" comes bursting out of the speakers in a rush of barely contained emotion and sports the type of thrilling chorus that fills your heart with joy as you breathlessly sing along.

The rest of the album has the same sonic impact and emotional power as it alternates between new wave-influenced rockers ("Goodbye, Goodbye," "Drove Me Wild") and moody and dramatic midtempo tracks ("Love They Say," "How Come You Don't Want Me") that wouldn't have been out of place on an early Cyndi Lauper record, before finishing with a pair of bleak synth pop heartbreak ballads ("Now I'm All Messed Up," "Shock to Your System") that make La Roux sound like Bananarama.

After a long career spent making subtle adjustments to their approach, it took some real guts to make such a drastic change, and the gamble pays off for them.

Heartthrob is the sound of Tegan and Sara taking on modern pop music head-on and winning in triumphant style.

One would have to go a long way to find a pop record that is as easy to swallow, yet contains such depth.

Welcome to the mainstream, Tegan and Sara...thanks for classing the place up a bit.