Kodiak, like Trevor says, there are others who know it and can explain it better than Dennis.
The angles are formed between the listener, the wall, floor, ceiling and the speaker. As you move your MLP closer to the speakers, there is less wall, floor and ceiling in front of you to reflect and you hear more of the speakers. The opposite happens as you move further away. There's a region where the direct energy from the speakers is the same as the reflected energy from the reflecting surfaces.
As you move closer, you may feel as if you are on stage or in the first few rows of the performance. As you move further away, you may perceive that the performance is "out there". I prefer the latter. As I turn it up, I get more envelopment that makes me feel that I am there with them but not right beside or in front of them.
There is no right or wrong distance with well-designed speakers. It's a matter of preference. Of course when you are dealing with multi-channel, you better understand which way you prefer before setting the equipment up.
Notice I said there is no right or wrong with well-designed speakers. A well-designed speaker is one that has a well-behaved family of curves like Toole has said. This makes the speaker sound tonally similar whether you choose to sit closer or further. The only difference is in the nature of the spatial imaging as I described above. This is certainly the case with all properly placed v4 that I've heard.
