Are upgraded power cables really worth the money?

I am amazed no one has mentioned upgrading your electrical circuitry as the biggest bang for buck improvement in this area. I spent a few hundred dollars and added 3 dedicated audio circuits to my main listening room. I think that is by far the most cost effective change you can make, and the one an audiophile should consider first. For about half the cost of a mid priced fancy cable, you can make a permanent change that will likely dwarf what any one cable can do for your system.
I have always considered Audiogon members a great source of information and inspiration - I guess this is a chance to "give back" to the community. BTW, all of these changes and improvements are so dependent on individual rooms, equipment, wiring, etc., so you still need to match the advice to your particular situation - there really are no absolutes.

Based on your components, I would try Audience powerChord. These should also do good on the amplifier. You should be able to determine with these power cords what they do and do you like what they do. they can easily be resold.

No, the cabling should be changed to the source, that is the power plant, anything short of this is a waste of money.

Remember, always be most careful of what you can't hear.

Previously, I had no opinion on the matter because I had not tried quality commercial aftermarket cords in my system.

Just got some Black Sand Siver Ref MkV w/ upgraded Oyaide plugs.

These cords made an easily noticable improvement in the sound, esp. the bass which is much deeper and tighter.

I can't beleive that someone couldn't, with the right but still simple test equipment, measure this effect and put this whole thing to rest, the change seemed so significant.

Only you can decide if it's woth the $$.

Should have added - One cord for a VAC PA100/100 amp and one for VAC Standard LE MKII pre. In comparison to Volex 14 ga that I had put upgraded ends on.