I'm experiencing a buzzing noise with my LD 1+ amp. My setup is PC -> Hifimediy U2 -> LD 1+ -> Grado 325i. It is dead quiet if there are only headphones plugged in as in no tubes or source. If the tubes are put in then the buzzing starts even when the volume is at 0. If the source is connected then some more a different buzzing occurs if the volume pot is turned to max in addition to the previous buzzing. The one exception to this one pair of Mullard tubes that are dead quiet. This happened once before, but the buzzing that time was due to a noisy dac, which I have already changed. I recently moved into a new house, so could it be something about how the new house is wired or something about its electricity? I've tried plugging it straight into the wall and moving it away from the router to no avail, so I assume it's not interference or a ground loop. I'm really at a loss because this only started happening in the new house and interference and ground loops are usually the two main causes of noise. Any help or suggestion is very much appreciated.