You write:
I'm very neurotic about this purchase because I remember swearing some time along the line that if I ever got to the point of swapping *power cables* my hobby had gone too far and I required hospitalization. Funny thing is, I feel fine. Muah-ha-ha-ha!!!
I think this is a common problem with power cords and some other tweaks that do not seem to have a reasonable physical explanation. I didn't either want to be a freak going too far but said to me that if you want to know the truth you must try (do not mean some kind of absolute truth but how it would work in my system). It worked very well. Typically as you connect more or better power cables, bass becomes tighter, you get better resolution and soundstage and most importantly, listening becomes much more enjoyable and involving.
Basically, good power cords clean up some of the distortion in the AC induced before the wall outlet and shields against RFI and EMI affecting the power cord (stock cable is not shielded). Wire acts as an antenna both before and after the wall outlet, and also collect disturbances from a large number of appliances connected to the power line, in your home and outside your home.
Effects of power cords my vary with local conditions. I live in an apartment in the inner city. The power line is shared by many users and there should be a lot of RFI from cellular phones and many other kinds of radio transmitters.
I have only three power cords so I can't say so much of the relationship between price and effect. I think there is a relationship but there is obviously also a lot of marketing hype about power cords as well as IC.
A common advise is to spend 10 % of the budget on cables. I calculated that I have spent 28 % on IC and speaker and power cables. This is 18 % more than the standard. However, the system improved substantially by the cable upgrades and I doubt very much that I could achieve the same improvement by buying 18 % more expensive components.
I do not think that it is meaningful to compare component upgrades with cable upgrades. Cables cannot improve components, only show what the really go for. But it is easy to suspect components to be insufficient when cabling is the real problem. I will give you an example. When I upgraded my CD player I moved my components and unplugged and replugged them. When I reconnected the AC to my Headroom Maxed out Home a fuse blew in the service panel. The MOH worked but sounded so bad that I suspected it had been damaged. Later I discovered that the problem was solved by a power cable. The much higher resolution and dynamics in my new CD seem to have made the powerline noise more hearable. I can also hear a clear difference when I A - B two power cords on the MOH, one is clearly better than the other. And the same when I change power cods on the CD. I have repeated this with the same result on another CD and on the power amp.
So, if it doesn't sound good, suspect cabling and system synergy in the first place and components in the second (if these are not obviously mismatched).
I don't think powercables should be the last step of finishing. Power cables primarilly removes distortion and do not change the character of the system. It doesn't become too bright or warm by this but rather reveals the character of the system. For example, a neutral, high resolution IC may sound too hard without power cables but very pleasurable when AC noise is decreased by power cables.