Thanks for all the input. Just some background info on the basics.
-Everything is plugged into the same outlet
-The exact combinations of preamps and amp are silent at a friend's house
-all outlets are properly wired
-yes it is a 60hz hum
-I have tried a preamp with no ground and a captive cord as well as another preamp with a grounded cord...makes no difference in the hum
I actually had an electrician that has done work for local recording studios come out yesterday and even he is befuddled. The only things he came up with were that the ground rod is corroded outside the house and he thinks the contact from the grounding wire is poor. He will replace that. Also, one of the electrical panels is inside the room and he thinks there many be some noise being induced by the proximity of the panel. He's the 3rd electrician and it doesn't seem to matter which amp and preamp I put in the system. Even matching preamp and amp from the same manufacturer causes the issue (with shielded IC's and various power cords)
Do you have an AC volt meter/multimeter?
Is this still your current system?
schw06's system, a Two-channel Audio System by schw06Room Size 17x24x10
System Overview
Room Description
17 x 24 x 10 feet
Acoustic Treatment
GIK Acoustics diffusion
Components
Digital Source
Lampizator L4 Gen 4.5 with Duelund caps and volume control
Preamp
Melody Pure Black 101
Power Amp
Thor Audio TPA-60 monoblocks
Speakers
Meadowlark Audio Shearwater Hot Rods until Intuitive Designs latest creation is delivered.
Interconnects
Dale Pitcher designs
Power Cables
Abbingdon Music Research
Racking
Sistrum
Power Cond
PI Audio group Uberbuss
-Everything is plugged into the same outlet
-The exact combinations of preamps and amp are silent at a friend's house
-all outlets are properly wired
-yes it is a 60hz hum
Exactly what all do you take over to your friends house?
Just the preamp and power amp?
How about the power cords for the two units?
How about the ICs used to connect the preamp to the power amp?
I doubt you take the speakers with you.
Power cords would be a must. They appear to be after market. It is possible the AC polarity could be crossed in one of them.
If we rule out a ground loop. Just curious did you try a ground cheater/s to lift the safety equipment ground for a test?
If the hum/buzz is not heard through the speakers when nothing is connected to the inputs of the amp and the equipment grounds to the equipment are lifted when the preamp is connected to the amp and the hum/buzz is heard, I have a problem with the problem being the AC power at the wall outlet back to the electrical service. I am not saying the problem is not from the wall receptacle to the equipment.
He's the 3rd electrician and it doesn't seem to matter which amp and preamp I put in the system. Even matching preamp and amp from the same manufacturer causes the issue (with shielded IC's and various power cords)
The speakers are always the same, yes?
The only things he came up with were that the ground rod is corroded outside the house and he thinks the contact from the grounding wire is poor. He will replace that.
Important for lightning protection. I doubt that will solve your problem.
Does the electrician have a power analyzer he can connect to the mains power?
That would tell him if you have an AC power quality problem.
How old is your home?
Electrical, service?
Electrical Panels, is there one on the outside of the house and one on the inside of the house?