Do speaker cables really make a difference ?

Depends on your system. This one likely can't be improved with speaker cables.  

In my humble opinion if the cables have sufficient insulation and are the correct Guage for the power you have and high conductive core. anything more is a waste of money!!

I did not read other posts, and this is the feedback from my own system. The cable differences in my system from most to least improvement is as follow: power cord for generator/conditioner; power cords for sources including streaming and disc transports; interconnects from DAC to pre, speaker cables, interconnects from pre to amps, and all others have small effects. 

Yes, they can make a significant difference. I had some custom made 1950’s 12 ga bi-wire NOS Western Electric cables on my Vandersteen 2CE Sigs, and when I got my Treo’s, a pair of AQ Comets were thrown into the deal. I didn’t initially use them, as I thought my NOS Western Electric were very nice, (and indeed, they are), and I also needed AQ spades for the Comets on the amp side. Finally got some, tried them out, but thinking I could sell them off for a nice profit since they were thrown in with the speakers. Well, hooked them up, and it was one of those ‘wow’ monuments. I knew I could not go back the WE cables. They have been installed since, and are not going anywhere.

Cables, given the overall equipment, can make a big difference, but I think speaker cables can be even more dramatic than interconnects…..overall.

Everything in the signal path impacts the sound quality. How much of an impact depends on the synergy with the other components in the system, particularly in this conversation, as one would expect, the speakers. Many speakers are very forgiving, if you will, when it comes to speaker cables. My Apogee Acoustics Duetta II Signature full range ribbons speakers (recently completely updated and upgraded by Music Technology in VA) are on the other end of the spectrum and extremely speaker cable sensitive. So much so that the speakers would sound like crap in various ways depending on the myriad of unsuitable cables. I know there are other speakers cables that would sound good, but there are many at various price points that simply won’t work well. I’ll go with Jason Bloom’s advice from 30+ years ago and won’t even entertain at this point switching out my Symo cables I’ve had since soon after the Apogees were originally purchased by my dad in 1988.