I know none of what I say will make a whit of difference, but I need some typing pracitce, so here goes
I hear differences in my system every day. Sometimes I play something and it sounds like garbage, sometimes magnificent. No changes, just different day. The human ear is extremely fallable. How else do you think things like Dolby Digigal can work - processes that throw out as much as 90% of the original data?
At times I have done something, changed something somewhere and heard a difference in the sound. Then I have stopped and done back to back comparasons in real time before change and after - guess what? The 'diferences' disappear. I know you are convinced that your friend heard big differences with the change of power cords in his tube amps. Have you stopped to ask what actually caused the change, and try to track it down and maximize the benefits of the change? In other words, if the mere changing of an AC power cord made such a big change, there _must_ be something in the system that is being very suseptible to external change. Is that RF interferrence? EMI interferrence? Harmonic distortion on the AC line? Low AC voltage? High AC voltage?
"Tweaks" by themselves may or may not actually make a difference, but if they are blindly done as a fix-all band aid cure to some imagined problem, the results cannot be predicted. I know I am sounding like the Professor on Gilligan's Island, married to scientific procedure, but sometimes a good scientific perspective can accomplish a lot more than just 'tweaking' without any thought to the problem to be solved. Personally, If I suspected that my AC power was causing some problem, I would put monitoring devices on it to determine exactly the state of the power. If it was contaminated with interferrence, then a filter appropriate to combating the interferrence would be indicated. If not, I would look elsewhere.
My question is this: What exactly are you trying to accomplish with the power cord change, aside from it 'sounding better'? What 'problem' are you hoping to solve? If _I_ change the power cords on all of my equipment, will it all sound beter? If so, WHY? Does this question matter to you?
I am not trying to be a smart ass asking these things. I tweak my system all the time: as a matter of fact I did some work on my electronic crossover today, changing the slopes of the crossover of my subwoofer. From a perspective of making real improvements, just 'changing things' on blind faith makes no sense. I bet you would be surprised and horrified if you knew the tortured path your electricity follows from the generators, through the high voltage power grid, through multiple step-down transformers, phase compensation, fuses and whatnot before it reaches your house. And you intend to undo all the potential "problems" endountered along the way with the simple change of 6 feet of power cord? Have you given any thought to what those 'problems' might be?
So go ahead, swap out that power cord. I'm sure your receiver will sound much better than before. I'm sure it wouldn't dare sound worse for the change.
Now that I've gotten my typing practice, I think I can go to bed. Good night all.....
[This message has been edited by soundhound (edited January 18, 2003).]