Cable differences -- power, interconnect, digital, and in what order?


A friend of mine has been a real connoisseur of interconnects and speaker cables; he hears very subtle differences between them, mixes and matches them with different results, and experiments with upgrades (and reselling!). 

One thing he's never done much with is power cords or power conditioners. 

This raised a question for me -- to what degree have people found differences in source and interconnect cables vs. power cables? Are they all important to an equal degree for you? Where is the greatest impact for you?

And if you do find power cables to be an important factor, where have you started making changes in your system? Wall to amp? With source? 

Thanks for any thoughts. 

128x128hilde45
Post removed 

In my rural area power and noise doesn't seem to be a problem. I do have a dedicated line though.The most profound positive difference was finding a really good pc for the amp.Next was the digital cable which took me many tries to find 'the one'.Then ICs and SCs to complement the source.

@hilde45 i’ll give you my rundown. First I bought pretty much of all I wanted for my audio gear.B&W 800 Matrix.
B&W Krell BAFs. (Bass Alignment Filters) 2 ( balanced ). Krell FPB 600 amp. Rega ISIS CDP. ARC REF 5 SE >>> ARC REF 6 >>> ARC REF 6 SE. Then I kinda knew what I was looking for, especially for my speaker cables. I knew my B&W 800 Matrix had awesome bass. That’s also why I went with the Krell FPB 600 amp.
speaker cables, Straight Wire Crescendo quad wired I loved the Straight Wire Crescendo speaker cables especially that they are phenomenal with bass., that I went with a Straight Wire Crescendo interconnects balanced I did a lot of research and reviews on power cords and I went with Shunyata king cobra CX. Shunyata Sigma digital. Shunyata HC ( high current) power cord. Last, but definitely not least were my outlets. Once again, I did a lot of reviews and research and decided to go with Furutech GTX- D (R). Oyaide WPC -Z2. Oyaide WPC -Z. Now I just purchased last week ARC REF 750s. And found another Shunyata King Cobra CX for the second mono block  ARC REF 750. Haven’t hooked up the 750s yet. Probably next week.