The whole point of high fidelity playback is to reproduce exactly what is on the source material. Nothing added, nothing taken away. Therefore, from a cable, you want a length of wire which does nothing, so you want a length of wire with zero reactance and zero DC resistance. As that isn't possible, you want as close as possible to that.
A cable with higher than normal capacitance or inductance, or higher than normal DC resistance (ie a thin one) deviates from this ideal, and therefore *does* 'make a difference' to the sound. However, this 'difference' is a move away from the source material, which may make it sound nicer depending on the qualities of the original source, and whether the rest of your system is designed by an electronics engineer or cobbled together by an ex-hifi dealer selling snake oil amplifiers which aren't stable and blow up every five minutes because he has some weird ideas about the colour of screws or green paint or something...
I guess what I'm saying, I'll stick with short as practical thick speaker cables (like the old QED 79 strand), and interconnects made from whatever RF cable I have handy because I know they're contributing negligible to nothing to the path from source to speaker.
So with Kofi Annan hat on, you're BOTH right.
Cables *can* make your hifi sound 'different'. What they cannot do is make it sound 'more accurate' unless there are deficiencies elsewhere being masked by a lossy cable. This doesn't stop a lossy cable making a system with deficiencies elsewhere sound 'nicer' though, but not 'more accurate'.
You should spend your money where it counts though. All components mortals can afford are designed with compromises. Get inside and fix those. That's where the real improvements are. I was listening to an old Prefab Sprout CD last night on my Marantzenstein CD player, and not to put to fine a point on it, it sounded unbelievably, jaw droppingly good! Far better than a £40 eBay CD player ought to sound.
"Two very small men cutting steps in the roof of the world"