Dedicated circuits help a lot, but how much they help depends on the environment. Today inner city and suburban areas all have RF issues, but they are greater in inner city areas.
You can't do much about the condition of the transformers and lines to your house or the meter on your house. But from that point on, you can control it.
My DVD player, a modest and aging Pioneer DV-47A, produces quite decent sound and picture quality with my new dedicated circuits, power conditioners and SRA isolation system. The improvement over the undedicated circuits and my 1980s vintage sound organization stands is amazing.
My dedicated circuit begins on the house side of my meter where power is divided into a 100-amp circuit serving only the AV system and a 200-amp circuit serving the rest of the house.
100-amp circuit begins with the best commercial 100-amp breaker Square D makes and feeds into an 85-foot run of 0-awg armored BX copper cable cooked and cryo'd by Virtual Dynamics. The 0-awg added greatly to the cost but we used it because the run is so long we wanted a heavy enough wire to prevent loss of voltage. The 0-awg terminates into a Square D QO breaker box which distributes 5 AV circuits of 10-awg armored BX copper cable cooked and cryo'd by Virtual Dynamics, one for each of the mono blocks, one for digital sources, one for analog and one for the projector. The receptacles are Hubble hospital grades cooked and cryo'd by Virtual Dynamics. With all of this the quality of the power available to the system is pretty good.
Because we live in one of the lightning capitals of the world though, we still need top drawer power conditioners with the best surge protection circuits available. We chose the Transparent line for 2 reasons, first because it is among those that do not limit power and second because its surge protection circuits react in pico seconds rather than mere nanoseconds. The surge protection circuits were the reason we chose Transparent over the other conditioners that do not limit power.
Together with the resonance isolation properties of the SRA racks and amp stands, the result is a completely silent background from which the music springs, wonderfully rich low level detail, extended decay of notes and a wide, deep soundstage. Video images are free from noise as well (digital artifacts from the cable -- less from the DVD player -- are another matter).
