FWIW I use Cat 5 for speaker cables, and my power cords are DIY from clothes dryer cords just because I figured it can't be worse than a thin stock cord. But I've never sat and listened for more than a few minutes 'cause I have better things to do. I always have several things in mind I'd like to do that I'm pretty sure will have much more impact on sound than PCs, ICs, or SCs.
But - Assuming your system is up to date, maybe the first "test" you might consider is closing your eyes and have someone come in and set it up so there's not a big cart in the middle, and the speakers aren't straight and up against the wall. You'd probably hear that.
But - Assuming your system is up to date, maybe the first "test" you might consider is closing your eyes and have someone come in and set it up so there's not a big cart in the middle, and the speakers aren't straight and up against the wall. You'd probably hear that.