But of course they do.
To be honest, it was just a week or so ago when for the first time I actually heard a difference in cables.
I helped my cousin shop for speakers and he went home with PSB Imagine T's. He's got a Denon AVR-S700 receiver and had his previous Klipsch R-24F speakers hooked up "bare wire" style to it with Monster 16 gauge zip cord type speaker wire that he'd bought years ago at Best Buy. The dealer had loaned him a pair of Nordost Purple Flair cables to test. When we first installed both the speakers were very nearly as bright as those screeching Klipsch. We went back to his junky cable and that was gone, along with a LOT of detail. Mind you, the Nordost cables are 12 feet long while the Monster zip cord wire was only about 8 feet.
I made him a pair of 12 gauge cables like these:
Made out of Monoprice 12ga CL2 with Techflex sheathing, KnuKoncepts cable pants, Blue Jeans Cable locking banana plugs and heat shrink tubing.
With some minor room treatment, major repositioning of the speakers and recalibration of the Audyssey, the Imagine T's now sound GREAT.