Most Beneficial Cable Upgrade


All things being equal, which cable upgrade would have the greatest sonic impact/improvement on a high end audio (stereo) system?
1)Power cables
2)Speaker cables
3)Interconnects
I have heard that power cables have the greatest benefit due to their ability to reduce RFI (radio frequency interference).
Does anyone know the answer to this question?
matjet
I do agree that the standard electrical outlets in most homes should be replaced; weak grip, thin contact material, cost the builder maybe $1 per duplex plug. Changing them to a higher quality plug is worthwhile and relatively easy if you are knowledgeable about electricity, circuit breakers and tools, cost me $7 per plug to replace with 20 amp heavy duty plugs. You can also buy the $50 cryo treated ones but that means 2 less (SA)CD's in your collection ( per). Interfaces are where most signal degradation/interference occurs.
I borrowed several simple devices, which measure noise on an AC conduit. One was Monster Power "Dr. Power" and the other was AudioPrism "Noise Sniffer". The devices seem gimicky but yield startling noises.

During the test, I unplugged the ice machine and two refrigerators. The noise was substatially reduced. I still heard static, motor whining and switching clicks. I unplugged the back-up UPS in my office and the static disapeared.

I went outside and heard my neighbor's swimming pool pump running. When the pump switched-off, I ran inside and noticed the motor noise had disappeared. I never found a local source for the clicking but suspect an old capacitor bank on the utility pole about 1/2 mile from my home.

Later that month, I purchased a used Monster Power "Monster Pro 2500" power conditioner for $100. I plugged both noise devices into the Pro 2500 and there was silence (even with the ice machine and refrigerators cycling).

I was amazed how much noise regular household devices were feeding-back onto my Stereo-dedicated AC conduit. Hair dryer, clothes washing machine, central air handler, central vacuum, VCR, food blender, bathroom exhaust fan and microwave ovens were offenders.

Now, I am ready to experiment with special power cords.
Bruce,
I agree about the noise problem in electrical line. This is one advantage of dedicated lines for power amps. It eliminates noise and draw from household electronic appliances. It provides cleaner power and more stable power.
Need to carry that thought a little further. A dedicated line doesn't provide that much additional isolation if on the same phase circuit as all other circuits in the house... all of those circuits are connected in parallel at the breaker junction. To get better physical isolation your dedicated circuit needs to be on the phase connection with least amount of other disruptive devices. Most houses are at least 2 phase (220 volts) and if you have a monster power need you might be 3 phase. Most junction boxes take the easy approach of loading up all their single phase circuits on 1 phase tap. Can't say that i've played with this but you can likely run from the second phase tap for a single phase circuit
GSSELF
Power cable audition update:
My dealer delivered only one of two amps ordered, one is still on back order. He did not bring power cables, he said next time he will bring some.
He feels better power cables have more of an effect on sound than interconnects and speaker cable. He said the better power cables have improved inductance is more efficient in delivery of elctricity (current?) to the amps. I have known him for many years. He has always been extremely honest, never steered me wrong.
It may be a few weeks before I am able to audition the cables.