wgutz ,
Thanks for your informative response.
The reason I asked in an earlier post what country you live in is because when I checked your profile, country was listed as N/A. You might want to change that to USA.
Now that I know you live in the US I have a few questions for you regarding the AC power delivery system used to feed your audio equipment.
What manufacture of sub panel are you using? Copper or aluminum bus?
Feeder size wiring feeding the sub panel?
Sub Panel wired 120/240V?
Approximate length of dedicated branch circuit wiring from the sub panel to the receptacle outlets feeding the audio equipment? (Up down and all around)
Type of branch circuit wiring used?
Example:
2 wire with ground NM-B cable? (Romex is a trade name). If romex how was the cabling ran through joists and or wall studs? Though a common bored hole or individually bored holes? If separate bored holes how far apart were the holes apart from one another? There in Romex cables kept separated from one another.
3 conductor MC armor cable? Aluminum or steel armor?
Conduit with wire loosely pulled into the conduit? If this wiring method was used was a separate conduit used for each 120V dedicated branch circuit?
Are all the dedicated circuits fed from the same line, leg, from the sub panel that feeds audio equipment that is connected together by wire interconnects? All fed from Line 1 or all from Line 2. (Not from Line 1 and Line 2.)
What are you using for wall outlet duplex receptacles? Manufacture, style and or series number? Plated contacts? Type of plating?
What material is the supporting back strap made of? Steel? Brass, other?
What are you using for cover plates for the wall duplex outlet receptacles?
Plastic? Flexible nylon? Stainless Steel? Other?
All the above can have an impact on the sound of your audio system.
.