Thought underground house shows were limited to secret rock throwdowns in grungy Allston basements? Think again. Groupmuse is a platform that applies the formula to chamber music, taking it out of the gilded hall and into your living room, in Allston or otherwise, where local talents perform short sets perfectly suited to millennial attention spans. An ingenious way to make classical music accessible and affordable for younger audiences, Groupmuse encourages attendees to drink, kick back and even get a little rowdy to the sounds of Brahms and Beethoven at BYOB concerts hosted by volunteers in homes around the city. Make that cities, now that Groupmuse has spread from Boston to New York, San Francisco and Seattle.