Arrangement of components on rack

Now and again -- though not often enough, probably -- I spend some time unhooking and unplugging everything in my system, dusting the works, and then setting it all back up again. Makes me feel better, and it seems that the simple act of unplugging and then reattaching cables and power cords etc. improves the sound, too -- if only in my mind.

As I'm getting ready to do that now, I just had a thought: Is there a generally accepted arrangement for components sharing a rack? What I mean is: Are there components that ought be placed close together and those that should be better spaced out? My power amp sits between my speakers, with the rest of the gear over on the side wall.

I've got a turntable, so that takes care of what goes on the top shelf. The other components: A preamp, a separate phono preamp, a CD transport and DAC in one box, a Bluesound Node streamer.

With all else equal, should, say, the phono preamp and the preamp be near each other? Far apart? does it not matter? I've generally just kind of plunked things down and gone from there -- and haven't experienced too much trouble -- though some years back when I had the preamp (the main one, not the phono pre) up close to the turntable I had a bit of hum, so put the preamp on the bottom shelf and have continued to do so.

Still, as I got to wondering and am set to get to work on this soonish, I thought I'd ask if there's a generally accepted way of arranging things.

Thanks very much.

-- Howard

Tube amp farthest away on the top (for cooling) on one side...turntable furthest away on the top at the opposite side.

Preamp as low as possible below amp (for microphony),  phono preamp and CD player below turntable.

In my case, when turning on from turntable to amp, the motion creates a smiley face right to left. Another smiley face from left to right to turn off. Easy for the wife and select guests to remember.

I have two dedicated audio lines and use one outlet for amp only and the other for all low level 
components. The turntable and CD player go to a Furman 2 component conditioner placed on the floor below the outlet. Preamps go to a 2nd Furman 2 component conditioner. Both conditioners sit in a low profile hardwood base off the floor and are always in the 'powered on' position. This fits in the 3-4" gap between the rack and wall.

This allows me to run signal and power cables in a manner where they cross at 90 degrees. I had some low level hum issues and the cross arrangement eliminated it.

I try and keep digital with digital and analogue with analogue and separate digital from analogue with copper sheets (Micheal's Craft Stores).  It's drops in the bucket but if you put enough in eventually you have something.
It is a rare component that is really critical as to location.  Onesuch is the Counterpoint SA-2 tube headamp, which must be as far away from the turntable motor to avoid hum.  And its detached power supply as far away from all the components as possible.  Other than that, I've never experienced a reason (other than ergonomics) to not stack them any-which-way.
Sounds like you have already covered the main step. Richard Vandersteen has always recommended the shortest speaker wire connection you can. If you have to run a long length it is better to have long interconnects. I run mono blocks so have pre in middle and each amp close to the speakers they power. My system is full balanced except phono. DAC and cassette are both balanced connections.