New room, 12'x17'

I am thinking of planning a room within a room in my basement. I like my current setup but am considering a projection video system. It would mean constructing a partition and the space would be 12' x 17'. The screen and seating would be 17' from each other and the screen and speakers would be on the short wall. My problem is this: I am concerned that I will degrade the sound of my two channel system and music is more important than video. Are any of you using a 12'x17' room for 2 channel? How do you like it and how are your speakers positioned? I am using Von Schweikert VR-4JRs plus other VSA speakers for the surround modes. The screen will be 100-120" diagonal, taking up most of the wall. I'm not sure I want to do this if it makes 2 channel worse, but who knows, it may be better! Thanks in advance for your opinions.