I agree with everyone else that once you set distances, speaker levels, etc., you shouldn't necessarily have to tweak any further. However, I still find myself changing things on occasion. I don't follow the rules!
For example, I've got a Denon 3802. Technically, my listening position is 9 ft. away from the mains. Well, it turns out that I wasn't satisfied with the receiver set this way because the soundfield sounded flat to me. After some experimenting, I was happy at 11 ft. Anything more, the sound became too loose and the soundstage fell apart. I also set the surrounds 2 ft. further as well so the delay wouldn't be off.
Then for the levels, you can use an SPL meter. Some people swear by these things. However, I'm not sure if they can account for room reflections. So, I used it as a general guide to set the levels, but used my own ears to tweak them to my personal tastes, which was to slightly increase the decibels of my surrounds. However, sometimes I still go in and change the levels on occasion, depending on what I'm listening to.
Anyway, I doubt I helped in anyway...but, I just felt like babbling!
