Yeah i have my sensitivity for my monitors balanced at -5db since the signal
from my usb mixer is strong.
I use a Furman power conditioner and also an APC ups and i get no hum. but the wiring from this house is also very good since its newer (1990).
I always have had the apc ups and an apc line conditioner (the line condition is in the picture. but it never addressed my sub's turn on thump). yet they can't fix how your house is wired. every outlet in your house is ground together, otherwise your electrician is a crook. these circuit is great for protection against shocks and fires, but not necessarily great for computer and audio equipment where you can get interference from these exact same things. if you have an orange plug then you have an isolation circuit. this circuit takes 4 wires (which you need 12/3 or 14/3 wire which doesn't count ground as a wire) instead of the usual 3.
the bare ground that come with it goes to the nearest common ground, which is why it's a good idea to place it next to an existing circuit. the hot and neutral stays in the same place while the 4th red wire (which is usually the other positive in a 240v circuit) get 2 pieces of green or black tape taped to it's end to keep electricians from getting confused. then you wire them to the ground of the circuit and the ground of the electrical box.
this keeps the common ground intact, while also separating that ground of that particular circuit away from the other grounds of that house. you've basically made yourself a 10,000.00 or more surge protector/line conditioner for 40-50 bucks and this circuit has better protection than those 10,000 protectors.
the only place most people see these kind of circuits are in hospital where they have real expensive equipment.
if you know a little about electric wiring, I can save you money. I've been stopped buying those expensive line conditioners. I always make me a circuit just for my stereo (it wasn't an isolation one though, which I've learned is better). instead of running 14/2 wire with a 15 amp breaker to it, I'd run 10/3 wire and add a 30 amp breaker to it and I guarantee you that you will never see that sagging voltage that you experience when are at the outer limits of a 15-20 amp circuit.
I post pictures in a minute of the circuit
Edit. Don't ever try this if you are unfamiliar with messing with an electrical box as this can cause bodily injury and even death. I am not responsible for your actions.
Audio Isolation Circuit
Now i can't wait to get a good soundcard..
