I just borrowed a nothing special titan star wired mains block costing £100 from a dealer and 3 power cables (£150 each). Plugged them and it makes an appreciable difference in slam and slightly more clarity. I’ve got one cable into the block, and the other two into my two cyrus power amps. I’ve done this before on a lesser system I had and I was thinking any improvement was bias, but definitely not now. Interesting.