Do speaker cables really make a difference ?

Like almost everyone on this thread, my answer would be, very much, YES. But, as usual that answer means absolutely nothing unless you hear the difference yourself, and like what you hear.

It seems to me that the key issue for anyone in your situation (and mine) is to have a nice hi fi dealer who will lend you stuff so that you can make comparisons.

Confirmation bias is real and very common here.  Not saying cables don't matter but when two cables are close, 2 component are close, a new component is added that doesn't make much difference, tubes are swapped, it is easy to get confirmation bias.  

I am certain many of the positive reviews here on the forum absolutely reek with confirmation bias. 

So do your tests for several hours each.  Keep an open mind.  go back and forth a couple of times.  Do everything you can to keep from being a victim of confirmation bias.

Sometimes I just do the upgrade and don't try to judge it, other than to confirm I did no harm.  

Jerry

Yes they do, regardless of what others may say. They really do.

"  Do not be fooled by the diameter of the external plastic sheath: what matters is the metal content of the core. The more the better, without exception….”

How much metal content of the core shoud be in good speaker cables ?

A couple of comments on "confirmation bias":

The exact opposite effect can happen as well -- rigid skepticism. When a new/different concept is introduced, there’s the prospect that it may peg the needle on our "BS meters". Everything we’ve been taught, our life experiences AND our common sense tells us that it can’t be true. Then, the unthinkable happens. We actually give it a listen and <insert EXPLETIVE(S) here!!!!>.

This is exactly how I was dragged kicking and screaming into what are modern staples in quality audio reproduction. As an avid skeptic. As a dealer in the mid 70’s I made a "courtesy purchase" of some meaty speaker cables. The "courtesy purchase" occurs when you like the rep (or find them to be somewhat credible, or both), or his company, and just what to make them happy (or, shut them the heck up). These massive cables hung on the pegboard for months, sealed in their factory packaging. During each monthly visit, I would be asked if had listened to them yet. The answer was consistent: "I haven’t gotten around to it yet". I’m not sure of what the actual motiviation was, but I finally broke them out and took them home. We’ll just say my life has never been the same since I discovered that certain cables shouldn’t be used on a quality 2-slice toaster -- much less a piece of serious audio gear.

Fast forward 20 years, and a concept that is often rebuked here was introduced. Same mindset. Same hesitation. But, I was finally shamed into listening. Yep. Eye and ear opening. That’s when the terms "intellectual" and "humility" became permanently engrained of my vocabulary.

Here’s MHO on cables in general:

I’ve experienced situations where a smaller gauge, well-engineered cable kicked the crap out of a big gauge cable in 95% of the audible range. There’s more to this cable thing than mere gauge or the purity of copper.

I’ve never experienced a system at any price that could not benefit from the (right) cable being attached. This includes $300 shelf systems.

Cables upgrades can make as much of a difference INSIDE of a enclosure or chassis as they do on the outside. Be adventurous. Pop the top off the chassis, or pull a woofer and look inside. You might be surprised at the upgrade opportunities that await you.