Speaker advice

Hi there,

I'm trying to figure out which kind of speakers would be the best choice for a sound instalation in a museum. The audio consists mainly in ambient sounds and music with some outdoor sounds as well, therefore very good fidelity and a large frequency range must be important factors to consider. The tricky things are: a) that the listening area is a circle (12 m. diameter x 5 m. height = 565 cubic meters aprox) in which the audience will be walking constantly or standing anywhere in the space; b) the audio signal will be stereo; c) the volume must be at a level good enough to fill up the space but not loud to avoid disturbing the other museum instalations.

I thought of using two or four 3 way main monitors Genelec 1039 along with one or two Genelec 7071 subwoofers, but unfortunately this goes way beyond the budget, and I'm not sure if all that power is necessary as well. Any suggestions?