It seems to me that if you're worried enough about power quality for long power cords to be a concern, you should be worried enough to get a power conditioner. You can pick up a Furman rack-mount at Amazon for something like US$65. I bought one about 15 years ago, and it has been feeding my various stereo and home theater setups ever since. I noticed a difference in TV picture back before I went digital, but it's been so long since I worked without one I can't really tell you how big that difference is.
Personally I'm not too worried about it. I think a power conditioner is nice, especially given all the electronics and appliances on my circuits, and or the the price it's worth it to me. I'm considering getting a second low-budget Furman for my computer audio setup. It's only 3x the cost of a decent power strip! But that being said, I've personally never noticed any power source noise through my audio equipment. YMMV!
I'm obviously no expert on the matter, but since you bumped your own thread and no one else has piped up, I thought my tiny bit of experience might be better than nothing. If anyone else pops in, you'll probably want to ignore me and listen to them 