Your house shares a circuit with the 950 and everything else, the ground. If there is a bad ground or some leakage to ground with electrical appliances it can show up in you 950. In an ideal HT setup all the components share the same common ground and it goes to earth. If there is a difference in the grounds some voltage may be generated and we get loop hums and sometimes rice crispy sounds. Power conditioners make it easier because they become the common ground and isolate the system from ground disturbances. Try plugging your 950 into an extension cord and plug it into a different circuit to see if that helps. If it does, then look at the receptacle you normally plug into to make sure it is well grounded and the wiring is all tight. Any switch or receptacle on that circuit should also be checked for the same thing. Over time, circuitry loosens and corrodes such that the connections degrade.