M for Montreal on Friday and Saturday is more like a traditional music festival, such as SXSW and CMJ. Venues all over the city host shows that are open to the public as well as festival-goers, meaning it pays to show up early to an in-demand show.

On Saturday night, due to timing conflicts, people had an even tougher choice: Head to a gig by Death Grips (a hip-hop group currently feuding with its record label) or try to squeeze into a very sold-out Of Monsters and Men show.

The latter won out for Diffuser.fm -- and it was a worthy choice. Of Monsters and Men used an arsenal of colorful instruments (including trumpet, accordion, piano and extra percussion) during a feel-good set full of whimsical indie-folk.

The Icelandic sextet (which last night also had trumpet player and accordionist Ragnhildur Gunnarsdóttir adding color) has had a banner year on the strength of its jaunty single 'Little Talks.' Naturally, the song was a highlight -- jubilant and celebratory, and buoyed by trumpet and drum solos.

Unsurprisingly, the audience responded enthusiastically throughout the entire 75-minute set. At times, fans singing along nearly drowned out the music, and whenever a band member asked people to clap, repeat lyrics or wave, the request was met with immediate action.

Of Monsters and Men were clearly delighted by the support -- after all, just one year ago the band played a far tinier venue at M for Montreal, so this was a triumphant homecoming of sorts -- and fed off this energy. The upbeat, accordion-driven 'Mountain Sound,' a coed duet between vocalists/guitarists Nanna Bryndís Hilmarsdóttir and Ragnar þórhallsson —was a dance-worthy celebration, while the quieter, acoustic 'Lakehouse' became a communal singalong.

The set-ending 'Six Weeks' was even more dramatic: With trumpeter Gunnarsdóttir banging on a drum to add noise, the song crescendoed to mimic a roaring thunderstorm. The song especially pointed to one of Of Monsters and Men's biggest influences: Montreal hometown heroes Arcade Fire.

The comparison isn't facile, though. The piano melodies by Árni Guðjónsson also draw urgency from plinking repetition, and the way the entire band sang along and shimmied onstage -- especially animated drummer Arnar Rósenkranz Hilmarsson, a livewire who practically vibrated behind the kit -- created fuzzy goodwill.

Unlike Arcade Fire, however, Of Monsters and Men tend to take a fantastical, less-serious approach to their music. Unison strokes of sound are common, and plenty of oh!s, la-la-las and hey!s dot the band's songs, and Hilmarsdóttir's regal voice always has an optimistic lilt to it, no matter how melancholy the song is.

If there was one downside, it's that the pacing of the set was somewhat off. Momentum created by brisker songs ('Slow and Steady,' 'From Finner') dissipated due to slower, less-engaging tunes ('Love Love Love' and a cover of Yeah Yeah Yeahs' 'Skeletons'). The show never locked into a steady groove until later in the night.

Still, Of Monsters and Men hinted at greatness during their three-song encore. 'Sloom' started off acoustically, which let Hilmarsdóttir and þórhallsson's strong harmonies dominate, while the show's final song 'Yellow Rain' transcended its “lullabye” description. Dying-music-box piano gave way to pounding beats and Hilmarsdóttir joyously banging on a drum and dancing like one of the Peanuts kids. The song got louder and faster as it progressed, ending on a powerful, uplifting note.

The night's opener, Sóley, specialized in piano-driven, minimalist compositions with skittering drums. While the introspective, thoughtful music was meticulous and beautiful, in front of a crowd amped for Of Monsters and Men, her quieter tunes got somewhat lost beneath the din of conversation.