Do expensive cables/wires REALLY make a difference

Yes. No question. You have to find the right cables for your system, room dynamics etc. I personally prefer staying with one companies cable at a time as this seems to sound best. Sure, cable companies make huge profits, but there are some really smart guys out there doing real r&d every day with real science, engineering, craftsmanship etc. I doubt, for the most part, that these are sleazy people in back rooms laughing at fools willing to throw money away. They're trying to run companies, feed their families and go home feeling like decent human beings, so even though it's expensive they're putting in their time. That being said, if retail is too painful, that's what Agon is for. Get serial #'s and make sure your not buying bootleg. I generally avoid anything coming from China, Asia, sorry, just my opinion based on experience. Companies would rather you buy retail but will usually confirm a cables authenticity if you ask nicely and they are high end enough to mark their cables with #'s.
Spend as much as you can hide from your wife and enjoy.

@rpnz  Let sleeping dogs lie.

I suspect that one of the problems here results from the fact that a little bit of research yields very different suggestions/ideas/products and therefore, confusion.... Here is a quote from Sanders Sound.. " At Sanders Sound Systems, we make no extravagant or false statements about our cables and interconnects. We do not claim that they sound any better than any other well-designed product out there. Our speaker cables are specifically designed NOT to alter the frequency response or sound quality of your loudspeakers. We believe that the speaker manufacturer knows how to get the best sound from their speakers and that we should not interfere with their design.  We offer two distinctly different types of speaker cable. One is for driving electrostatic loudspeakers and the other is for driving magnetic loudspeakers".


OK....how can you argue with the idea that each manufacturer of speakers or electronics that also sells their own cables would sell the cables that go best with what they make.  In that light....here are links to 4 different cables being offered by companies that primarily make speakers or electronics...and as you will see, the cables are all different from each other...and different from what you see being offered by the high end cable sellers.  No doubt, if you are considering upgrading/changing your cables, you will be more confused after you check these links.

http://sanderssoundsystems.com/products/speaker-cables-and-interconnects/speaker-cables

https://www.cherryamp.com/product-page/6-speaker-snakes-pair

https://www.decware.com/newsite/speakercables.htm

http://gr-research.com/b-6speakercables-2.aspx

I'm what you would call a skeptic (beyond a certain point).  I never used zip cord for instance, but won't spend a ton.

I try cables in and out of the system here and there.

I can say that I am 100% convinced that the USB cable upgrade to my DAC made a big difference, didn't want it to, went blind testing with a neighbor etc.  It made a difference.

Speaker cables, pretty sure I've heard one cable make a big difference form my 4S11 - Reality Cables, they brightened things up.  I don't use them, but I'm pretty sure it made a difference.

Interconnects, not hearing much, but use Mogami XLR so they are quality.

Power cords, where I was a HUGE skeptic. Happened to get a PS Audio AC3 as part of a deal.  Tried it on a few amps, I HATE to admit it, I'm 85% sure it made a difference, it wasn't expensive and so I kept it.  

Recently tried a few cords on my DAC... begrudgingly I think once again the AC3 made a difference (sharper, slightly brighter tighter sound).  Hate saying that, but AC3's can be had for just over 100 bucks. So why not.  Have one more on the way for my pre-amp.

(if anything, the better plugs are nice in the wall)

I did try a nordost power cord on the DAC and don't think I heard as big of a difference as I did with the AC3.  Again, makes no sense.  The electricity travels through literally miles of copper before it gets here, why that cord would make a difference - no sense to me.  Yet, I'm pretty sure it did.  Frustrating for sure.

But also borrowed a few high dollar power cords, didn't sound much different than the AC3, so not going there.