Want to see a professional orchestra or symphony perform? See the GMU Calendar for music events.
Or check the schedules for these area organizations:

Fairfax Symphony
McLean Symphony
Alexandria Symphony
McLean Orchestra
National Symphony
Millenium Stage at the Kennedy Center (free!)
Marine Chamber Orchestra Most concerts are free, and at NVCC-Alexandria campus
Reston Community Orchestra
Sunday concerts at the Phillips Collection Students 18 and under have free admission