Which components to isolate

Heyraz wrote "I would group components based on current draw, keeping the most sensitive components (preamps) away from the most current disturbing components (power amplifiers)".

Interesting. I was thinking along the same lines, but thought the most disturbing components were the digital units, so I'm keeping the DAC on one dedicated circuit and tube pre and tube amp on another dedicated circuit, and the computer an a non-dedicated line. Will try pre and amp on different circuits and DAC with either option and see if I hear differences.

How are others connecting/separating pre, amp, and digital?

I think amplifiers draw the most current and the amount varies by demand. I think digital devices are noisier, broadcasting artifacts as they rapidly switch on and off.

I'm basing this opinion on ground noise. A nice way to picture ground current is to view it as the flow of water down a river, it's current. Any stream that enters the river disturbs the current, the stronger the stream, the more disturbance to the current.
When you lay out the ground points in an amplifier, you group the most sensitive sections (input) away from the noisiest sections (power supply/rectifier).

If you're using three dedicated branch circuits from the main panel, you may experience ground loop hum. That's why I don't "electrically" connect my computer to my stereo anymore. Very noisy, hum.

Every component on my audio system is on the same line, absolutely zero hum. But every component is filtered from each other so when I switch on one component, I don't hear a "pop" in the background.

Every component with Symposium roller block HDSE wonderful great bass,stage imaging etc.

The ideal solution is very simple; regardless what type of isolation you are using. 1. Isolate your digital from all else. Then experiment. Try isolating the preamp and then the amp. Most likely you will be able to decide very easily. Have fun. Happy listening.