My experiences trying interconnects and speaker cables was 30 years ago and they made big differences for me. This was back in the days when you could take home cables and try them for a week at a time. My speakers have had tendencies to be a bit forward. So, to have my system open up and be revealing without being too aggressive has been a balancing act. The most “transparent” cables (Cardas, Siltech) could make my system overly aggressive. Once I settled, I’ve never felt tempted to try again. From my perspective, getting the components I own to play at their best is the icing on the cake. If I was still unhappy, I needed to upgrade electronics.
More recently, I have been amazed at the benefits of upgrading my digital interconnect and the power cords for my preamp and DAC. Relatively cheap upgrades the changed my perspectives on equipment I already owned. I had been talked into avoiding those upgrades as being needless and I was wrong.