Can too many components on one outlet affect the sound of an amp?

don't simply turn unused equipment off,  unplug it, especially home theater stuff...that was a recommendation from Charles Hansen of Ayre, and I find it to be very true in my system...

Yes, the fewer components, the better it sounds.

Yes. And turn off your microwave, dedicated circuits or no. I have 6 dedicated lines, and yet I can hear the microwave. It is not just this house: I heard it when I lived in San Francisco in my apartment, which also had dedicated lines. And I tested the theory out with a couple of audiophiles, who swore their dedicated lines protected them from that. It did not, as they heard within 1 cut of a CD.
And re: The Maestro. I like it too, but despite its naturalness, it lacks a certain ability in dynamic authority and pace and timing. I think it might be that slightly recessed upper midrange.

Using a proper power conditioner reduces the background noise level and improves the dynamics, besides protection from lightening and other hazards. One other thing that I did was lift the ground and do a separate star grounding that goes out of the house into the ground. This I do not recommend to all as it has its serious dangers, but made my system remarkably quiet. Having separate circuits can induce hum at times. 
Having said that, subtle changes in sound with any change may or may not be for your liking as we all hear differently.
thanks,
Giri

giri


  " ...One other thing that I did was lift the ground and do a separate star grounding that goes out of the house into the ground. This I do not recommend to all as it has its serious dangers ..."

Do you mean that your safety ground does not connect to the service panel's ground bus? If so, that is extremely dangerous and absolutely does not meet code, at least in the US.