How would you deal with neighbours? I have had the one living immediately next to my house and the one living immediately behind ring the doorbell asking that I turn down the system while listening to blues in my living room at what I consider realistic levels (well levels that Muddy Waters would have found realistic...). I have had them complain when playing bluegrass at a very very reasonable level on a terrible little portable while gardening. Strangely enough (or maybe not so strangely) no one ever complained regardless of volume levels while listening in my dedicated room in the basement. Maybe the double layer of plaster board (with joints taped and filled on both layers), on metal resilient channels, the fibreglass stuffed between joists and studs and the two small basement windows of that room have something to do with it.
The concept of doing what you suggest just once is interesting, if only to satisfy your curiosity. However, like Sean, I don't think you would improve your system by the mere fact of going through this experiment. Your speaker system is designed to be played in a room so that putting it out there with very little reflected sound is hardly fair. Maybe what you really need is an anechoic chamber. The price tag, however, would floor you.
As Rives would no doubt suggest: improve your room's acoustics by trying out the various improvements that have a basis in reality. Once you have done that, you can tweak to your heart's content. You probably won't feel like moving the whole tweaked out system to the backyard once you have done all the work required. Regards.
