I have been experimenting quite a bit with tweaks and often find they are nearly all very hard to hear or so small that I question the value for money.
I surprised myself with two AC and one BC sort kone from nordost.
These when put under my kit I struggled to hear a difference.. I tried a few tracks and also underneath the DAC, the PSU, the mains block and the amp.
Then I tried one ; the BC under the mains cable headed for the socket amd on a repetitive baseline I heard more bass, richer and prominent. Yes - I heard a difference and this was just under a the mains cable! The cable was not on carpet FYI.
A pair worked well under my mains strip.
I was ready to send them back, but think I'll be buying more!