Anyone who saw the Joy Formidable’s blistering set at Billboard’s South by Southwest showcase in late March knows that this Welsh trio doesn’t do anything small. Even the band’s 2009 indie debut mini-LP, “A Balloon Called Moaning,” had a big sound, big hooks and even bigger ambitions. The Joy Formidable’s new full-length, “The Big Roar,” ups the ante to almost comical levels. It’s a sprawling 50-plus-minute-long opus filled with stadium-sized choruses, wind-tunnel guitars, deep bass rumble and several canyons’ worth of echo. The twist comes in the three-piece’s unusual fusion of indie-pop and sonic skyscraping. There’s an early-’90s alt-rock lilt in frontwoman Ritzy Bryan’s vocals and melodies that’s toughened by the volume and intensity, so “The Big Roar” sometimes summons visions of the Breeders playing with Muse’s equipment (and drummer). It’s a killer combination of sweetness and brawn that’s best captured on the more compact songs “Austere,” “A Heavy Abacus,” “Whirring,” “Cradle” and “The Greatest Light Is the Greatest Shade.” The bigness gets the better of the threesome on several songs-but regardless, smart money says the Joy Formidable will be one of this year’s breakout bands.