Why is it necessary to have gear on the same phase from electrical panel?

Phase difference only applies in 3 phase circuits, houses are single phase. If you are stating one outlet is on other hot side (240 volts across both hot wires) vs both on one side (120 volts across to ground), it would not make any difference as the power supply on either configuration just converts AC to DC with the power supply capacitors storing the energy long term beyond the 60Hz.

I am sorry the post I was typing above decided on its own to post before I was finished. This site is finicky.

This is my issue with both plugs in an audio room having to be on the same hot wire. One side is grounded anyways &neutral) Hotside is grounded thru an average of 10 ohms with other items connected in the house and your audio gear anyways. A fe volts difference in an unbalanced load across both ht wires amunts to about zero infle

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

One side the neutral is connected to ground not matter what circuit hot side you are using. The hot is actually grounded too thru about 10 ohms load with other items in the house drawing current besides your audio gear and lower with AC running. What's the difference in noise with both circuits on one side or split by both hots?