Went down to Ohio last summer to hear some SM80s outdoors...2 SM80 over 6 TH118.
The most interesting thing, other than the quality of the sound, is that when out about 200', you close your eyes the sound seems much closer than it actually is.
I attribute this to the cohesiveness of the spectrum distribution.
I really need to get a pair!
Part of the miracle of our hearing system is that the brain can detect very small differences in arrival in a sound source.
So an easy test is to close your eyes for a little bit, and listen. If you can tell how far a loudspeaker is away (within reason), then there is some "distortion" of the signal coming out of it.
And by distortion-I am not talking about harmonic distortion, but rather that the sound coming out is not true to the original signal.
Yes all loudspeakers have all sorts of "distortions", that is why they are BY FAR the worst offenders in the whole signal chain in terms of passing a signal unaltered-even the very best ones are FAR worse than any electronics driving them. Mics are next in line. Then it drops down real far to the various electronics.
The better behaved the signal is, the more it will hold together over distance and the harder it is to tell how far away it is.
Another way to tell how well the signal is holding together, is to listen to how it behaves in the wind.
If it is blowing around (being subject to temperature variants), then it is not as well behaved as one that is more immune to the wind.
So a speaker that sounds good at a long distance with the wind blowing, is going to sound very good indoors and closer-because it is better behaved.
Especially outdoors, it is important to have as FEW of sources of sound as possible, to help the sound "hold together" at a distance.