Am I hearing things?

I just an extra  new dedicated line run beside the other one. with 10 gauge wire, 30 amp breaker and a 20 amp rated outlet. I don't think it sounds as good!!! What the hey. A little shrill in both vinyl and CD. I'm comparing from what it sounded like last night. Does electricians wire, breaker and outlet have to burn in? Am I alone in this. I'm have a whole system AC but in and the temp got up to 80. Maybe that is why. Also I'm listening at 11 am EST. So the power grid may have an affect. Did I just answer my own question or have other people experienced this. The original dedicated line was put in in 03 with 12 gauge wire, 20 amp breaker and a 15 amp outlet. Are these 2 lines picking up interferrence?