Múm is the latest in what seems to be a global trend of acts that believe the bigger the band, and the more unusual the instrumentation, the better. Though only two original members of the group remain, Gunnar Örn Tynes and Örvar óreyjarson Smárason, there were seven musicians on stage during last night’s concert at the historic 6th and I Synagogue. The ensemble employed the following instruments over the course of the show: guitar, bass,…