I have Harbeth C7es3’s. I was able to trial them and A/B them over months.
the other cables I use include Inakustik and Black cat, and Blue Jean.
these cables made a significant difference in the sound of my Harbeth’s. Enough to want to buy them. fwiw
Blue Jeans Cable Iconoclast
I find it odd that Blue Jeans Cables, who always promoted that higher end cables don't make a difference (especially power cables) are now carrying this pricey Iconoclast line.