The most quiet camera for classic music recitals

I just came across a problem when I had to photograph at a classic piano recital in a very quiet large room. The mirror in my camera (E-620) could be heard across the room so I had to stop taking pictures. I need a very quiet camera which will take a range of my 4/3rds and/or m4/3rds lenses. What would you suggest, which is the quietest?......btw, it needs to be able to take an OVF or EVF for focusing with tele lenses.