Washington Concert Opera (WCO)

Washington Concert Opera’s motto captures what a concert opera performance is about: "it’s all about the music." A concert opera is a complete, full-length opera presented with the soloists, orchestra, chorus and conductor on stage. There are no sets, costumes or props to distract the eye…and ear...from the operatic score. The focus is entirely on the performers and their dynamic interaction with their audience. There is nothing to upstage the music and dramatic interpretations at hand. 
http://www.concertopera.org