Do speaker cables really make a difference ?

Always. YRMV.

I find that speaker cables always make a difference and are system/taste dependent but may make less of a difference with speakers that are easier to drive (i.e sensitivity > 90dB and minimum impedance 6 Ohms+). Definitely worth exploring, and with so many direct sellers with generous trial periods and a robust used market (at least for cables from reputable manufacturers) there’s really no excuse to not try a few cables in your system. Best of luck.

@akg_ca 

Thanks for sharing your experiences.

Obviously related components can be a very important variable, and then there is the ever present question of diminishing returns. The other issue is that even if one wanted to A/B speaker cables, it wouldn't be easy to do, and for a variety of reasons.

Cheers!

Absolutely big yes, I just bought Kimber 8ag speaker cable . Iam enjoying the music more. 

As an ancient one I'm from the days when high end speaker cable was 14 gauge lamp cord rather than 16 gauge. It took me a while but there's no question different cables sound different and they probably vary depending on the rest of your system, especially the amp/cable/speaker combo. So I believe a lot of experimenting is needed(and cables are often costly).

By the way if the amount of copper mattered then the old Fulton Gold cables had to be the best. You could jump a jet engine with them. They were good and definitely not bright due to high inductance rolling off the highs a bit.