Howard, I think you have it exactly right. If anything is going to cause trouble it would be the amps electromagnetic field interfering with low level equipment particularly phono stages. Putting the amps as far away from everything else is the way to go. Between the speakers keeping the speaker cables as short as possible is best and that is what you are doing. If you can run balanced cables to the amp that is even better. But, for years I ran single ended cables without any difficulty but never longer than 25 feet. Some people might argue that with toroidal transformers distance does not matter but speaker cable length remains an issue and like you it makes my brain happier.
Turntable on top is standard for obvious reasons. The rest I do not think matters at all. I always try to keep power lines away from signal lines and always crossing at 90 degrees.
Turntable on top is standard for obvious reasons. The rest I do not think matters at all. I always try to keep power lines away from signal lines and always crossing at 90 degrees.