Nostalgia is a tricky musical ingredient. It’s forceful and poignant, but it can also leech all the originality out of your art. This is the crux of the balancing act that is LCD Soundsystem’s rebirth. Among the most revered indie rock acts to ever lace up Converses, the Brooklyn outfit has returned after a highly publicized farewell concert in 2011. There’s a certain element of nostalgia to any return like this. Will it keep pushing boundaries? Will it keep playing the old songs we love? The band seems to have mastered this rocky terrain: The act’s recent LP American Dream nods to the past but reaches for the tough questions demanded by our present. The pain and loss of aging, the quickening rush of time, the beautiful but disorienting nature of life as an artist: All get coverage. But American Dream, like much of the band’s releases, is also highly self-referential, charting the serpentine path the band has cut through the landscape of 21st century music. How it inspired a decade of listeners by fusing electronic sounds with post-punk-era art rock also comes across. All tickets include a CD of American Dream.