interconnects vs speaker cables vs power cords - which make the biggest difference?

My two cents:
Power cord....you must get the RFI/EFI right from the start otherwise noise will affect the chain of components to never return. I use Stage lll with a wonderful affect. Power supplies via manufacturer vary to a great degree so YMMV. Try on your TV to find out noise cancellation. The picture won't lie.
Interconnects.....source to preamp. next preamp. to amp.
Speaker Cable.....all to a varying degree but the least in my experience if the front end is taken care of.
Everything lost in the chain will never return so it all matters.
Gwalt

Why are we all trying to reinvent the wheel or beat a dead horse , allot of this has been done already in the 12V car audio world. If your into 12V audio you know the big three upgrade is done along with any decent subwoofer install , big three is upgrading your positive wire from your alternator to your batt, ground from alt to chassis , neg from bat to chassis basically a charging system upgrade cause stock sucks, Power cables are like doing a big three in your house it allows your expensive stereo to pull more power from your outlet it does help if you have a conditioner , run a blender in your kitchen and see if it doesn't show up on your tv in some way  , these expensive power cables also do a good job of keeping interference out because they are in effect just antennas and need to be shielded along with being able to conduct electricity better that's number 1 , 2 why on earth would you have an inferior speaker cable if you spent all this good money on nice towers , and 3 interconnect spend as much as you can afford without not being able to buy diapers audio quest Forest is good enough allot of the tech can be found in the even higher end cinnamon line there splitting hairs i think and is just an opportunity to rake more money out of you cause i can't tell a diff . power to stereo is most important , its also nice to upgrade the TV power cable but is not needed , Also Dudes get your apps thru your TV there is no HDMI for video except for the hdmi to your receiver for sound and let your TV networking cable go into your modem for Fast ethernet connection opposed to getting your content on a coax network Comcast verizon.... you have a bottleneck on coax and then have to come out of your verizon box on HDMI go to the stereo and then on to the TV .  If you have a netflix app on your TV its immediate no loss no HDMI cable for video  , i would say its still better having a blue ray 4k .       nicholas.giordano@att.net  love to hear your thoughts , please dont put to much thought into it. 

The "pecking" order for my small 2-channel system is....

1. Speaker Cables
2. Interconnects
3. Power Cables

If I had a large power-hungry amp, power cables might prove to be more important but my Bryston Integrated Amp doesn't seem to care what I feed it with. I do, however, replace OEM 18AWG PCs with generic UL-listed 14AWG ones because they're inexpensive and provide (in theory) better power delivery.

From an EEs perspective,  if power cables make a difference, then you've got a poor power supply design. 

I doubt that’s true since power cords oft make the biggest difference for amps with big robust power supplies. Good try, though.