You mentioned you're using linear supplies - linear power supplies use 60 (50) Hz transformers. Transformers vibrate, and it's noticeable at those frequencies. Switch-mode supply transformers typically operate at much higher (80kHz +) frequencies so you would not "feel" those vibrations. There are some very clean switch-mode supplies on the market, and their noise signatures are well above audio frequencies. Might be worth a try.
Why can I feel vibration when I touch my network switch or streamer?
I have a Silent Angel Bonn N8 switch powered by a Forester F1 linear power supply, which is attached to an Innuos Zen Mini Mk3 with a SSD, also powered by a linear power supply. The N8 and Mini sit on top of their power supplies.
When I lightly touch the top of either the N8 or Mini, I can feel a slight vibration. I am surprised by this because neither device has any moving parts that I know of.
Why does this vibration occur? Is it inherent vibration of the electrical parts within the devices (e.g., resistors, capacitors)?
Would I be well-advised to avoid stacking the N8 and Mini on their power supplies?
Should I simply decrease my coffee intake?