If you have revealing equipment, the difference is night and day, there is no two ways about it. To say they don’t make a difference doesn’t even just border on absurdity. True, quality isn’t cheap, and some manufacturer’s do sell snake oil in highly fashioned jewellery style. Though some manufacturer’s do a lot of R&D to get their products right, they can take an average sounding system and make it a truly involving experience, and once you have had that experience, you know what to look for. A mishmash of equipment and cabling and even the most highly expensive, (not that all of them are even good) and revealing systems will sound 2 dimensional, flat, poor soundstage, bloated bass, poorly detailed, lacking realism, rather like a cardboard cutout of your favourite model. Given well chosen and matched components and the right right room dynamics, a set of cables chosen well can open up a system, even one on a reasonably modest audiophiles budget to realms not thought possible without said cabling. Summing up, It’s not snake oil, but choose carefully, and have someone who actually knows what they are doing show you in your system in your home.