Most Beneficial Cable Upgrade

AC power cords and most other power "conditioner" products. The sales claims sound logical: Noise and static can get into your gear through the power line and damage the sound. In severe cases it's possible for power-related clicks and buzzes to get into your system, but those are easily noticed. The suggestion that subtle changes in "clarity and presence" can occur is plain fraud. Indeed, every competent circuit designer knows how to filter out power line noise, and such protection is routinely added to all commercial audio products. Spending hundreds of dollars on a six-foot replacement power cord ignores the other hundred-odd feet of regular wire between the wall outlet and power pole.The real answer is? Use logic and really listen with someone else but you doing the switching and you might just see the silliness of it all.

Schipo: all well and good. i used to scoff at power cords etc. Then i tried one that really made a difference in my system. The complaints are ALWAYS theory, the positive claims are alway experiential. The one area that one can SEE is a video screen. it really makes a difference on a good screen, like my Plasma.
So some stuff does have an effect, from my own experience. All I can say is if you do not like them, then do not buy them.
I agree that most of the aftermarket tweaks are overpriced garbage. Much of the stuff can be made with ordinary (cheap) stuff.
So all I can do is agree with you on the main, but still have to say i have found that cords do make a difference... though I would personally never spend big bucks on a powercord. (more than a hundred) But i have spent a LOT for a power conditioner (the Furman I found here on the gon' for $1,400. a good deal)

don,t we discuss this once a month? haha i think,,,can,t prove,,, that when i swapped my moderately priced ac cords out of my cd player, pre and amp and replaced with the stock cords that the bass sq went south of he--. i have also done this with the ac cords one at a time with similar results. i gave them a day and it never got better. when i put the moderately priced ac cords back in and listened after playing for a few hours tight defined musical bass returned almost immediatly but got much better over the next day.. can,t prove it but i heard it.. so i have decided that all my cords, cables and wires are going to be the best i want to spend on and leave it at that for now. i also don,t do a/bs because i think i can hear and know what my system and good systems are capable of. i could be wrong.

My point was that when you speak of upgrading it depends on what your upgrading FROM. You can't tell what the weakest link is until you know what the links ARE. That said, anyone who can't hear the difference between power cords in either profoundly deaf or has a crappy system. I have tried substituting cheap cords for good ones many times and have always been disappointed. I wish this was not so as I am as cheap as the next one. I think the reason many systems sound bad is insufficient attention is paid to peripheral gear.

Preamp to amp interconnect, then Speaker cables in my system. I have good PCs but didn't notice a meaningful difference beyond not using the $1 stock cords especially after dedicated circuit.