Iceland's Of Monster and Men performing at Billboard's Post Party at Chicago's Double Door. (Photo: Dana Loftus)

Billboard capped off an eventful Lollapalooza weekend Sunday night with a Post Party at Chicago's Double Door, presented by Starbucks Refreshers, featuring performances by Australian rock group The Jezabels and Icelandic folk-pop group Of Monsters and Men. Brooklyn electro-pop duo French Horn Rebellion kept the crowd amped between acts with a special DJ set.

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Though many fans filled the 500-capacity venue, a handful of industry execs were spotted among the Double Door's two VIP sections -- including Liana Huth Farnham, senior VP of partnerships and events at Fuse and MSG Entertainment; Alex Kirshbaum, a partner at artist management firm NUE Agency and chief operating officer of SoundCtrl; Ben Adelson, director of A&R at Of Monster and Men's label Universal Republic; Dan Reilly, editor at AOL's Spinner and several agents from Paradigm, Of Monsters and Men's agency, including Rachel Pestik, who's accompanied the band on numerous stops along their tour.

The scene outside Chicago's Double Door with a line down the block to get in. (Photo: Dana Loftus)

Of Monsters and Men delivered a triumphant hour-plus headlining set, a fitting coda to a busy period in which the seven-piece band played six shows in four days -- similar to the packed itinerary that made them a breakout at this year's South by Southwest in March. Manager Heather Kokler describes the post-SXSW months as exciting and fast-paced for the band. "We've been so busy planning and quickly putting together a schedule for these past few months, we haven't always had time to just sit back and appreciate what's going on."

The hard work appears to be paying off. The band's debut album My Head Is An Animal was released in the U.S. just two weeks after SXSW and debuted at No. 6 on the Billboard 200 with sales of 55,000 copies. Lead single "Little Talks" has been ascending the ranks of Billboard's Triple A and Alternative Songs charts, and currently sits at No. 59 with a bullet on the Hot 100, enjoying its 17th week on the tally. The single still has enough momentum that Kokler said a second single has yet to be decided, though some radio stations have begun playing album standout "Mountain Sound," a new track released on the U.S. version of Animal.

Members of Of Monsters and Men playing kissy-face. (Photo: Dana Loftus)

The band next continues the U.S. festival circuit when it heads to San Francisco's Outside Lands this week before embarking on a European tour through October and finishing the year for another U.S. tour in November and December. "We've even confirmed some things into early next summer," Kokler added.

Nue Agency's Kirshbaum was also celebrating a successful week, having seen client White Panda, a mashup/DJ act, play to a crowd 4,000 deep during their 1 p.m. set at Perry's Stage just two hours after Lollapalooza kicked off on Friday. Another NUE client, rapper Action Bronson, just closed a label signing that will be officially announced in the coming days.

Billboard's buzzy show was the latest in a series of events and media partnerships Starbucks has been sponsoring all summer as part of the launch program for its Refreshers beverages. Kate Jalkut, associate media director for Starbucks' media agency PHD, said having a presence around Lollapalooza was an ideal fit for the program with its "wide spectrum of artists" and "good representation of what we're looking to associate with in technology and entertainment."

Australia's Jezabels performing with rays of green light pouring forth from frontwoman Hayley Mary . (Photo: Dana Loftus)

Packed exuberant house (Photo: Dana Loftus)

Starbucks Refreshers sponsored the event: (Photo: Dana Loftus)

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