If differences are not immediately obvious,
a) it could imply that you have other bottlenecks, poor speakers, low resolution room, low quality ears, etc, which didn’t make it worthwhile for the cable upgrade to begin with.
b) it could mean that you bought some bullsht cable which wasn’t an upgrade at all.
p.s.
This whole suggestion of sitting for around for weeks to compare and discern differences eventually is foolishness (some guy seeking psychological solace, or some sales guy waiting for the return window to expire).

