I only bought my first 'proper' interconnect cables because I had read about them in magazines and because I was not happy with my system and thought they might be a solution. Ditto with speaker cables. If there had no been a problem I would not have bothered as money was tight way back then.
I think they were the Tandy 'gold' interconnects which were inexpensive but a flavour of the month at the time (1991-ish).
They did improve the sound but were not a fix for the problem which later turned out to be that the kit I was using was crap.
Still, you live and learn. The point was the Tandy leads did indeed sound both different and, to me, better than the freebie leads they replaced.