Noise Goblin

I moved into a 44 year home three years ago and it still had the original electrical box.  I had an electrician put the outlet I use for my audio system on a separate circuit.  Even still I was getting some noise through my speakers and when my wife was using the hair dryer in our bedroom upstairs I would get a buzz through my stereo amplifier.

Fast forward:  I just had a brand new electrical box installed with the latest grounding etc.  My audio system is on a separate circuit.  Low and behold this morning I started to hear the buzz through the stereo amplifier again.  I ran upstairs and my wife was using the hair dryer.  I am still getting a slight noise through my speakers. When I turn the volume up the noise gets louder.  

I don't understand how this is occurring.  Not sure what to do.  Are there any electricians or others who have had this same issue on this forum who might have an idea what is going on and how to correct this issue?