I can’t believe it, but I have had real improvements using Shunyata Alpha NR cables. I don’t think it is a matter of the conduction characteristics, but I think the filter they put on the cables does a lot to quite the noise of the bias supplies. I think the speakers are either susceptible to, or generate a lot of gunk in the system.
In the past, people had great luck with a Wattmaster cable with crazy shielding and filtering. I cannot recall the model, but it wasn’t on the budget end.