If your equipment isn't grounded and your interconnects have poor shielding then you certainly need the best shielded power cables you can find.
You'd be better off grounding all equipment first. An RF Router Plug-in from Russ Andrews with separate grounding cables from each case back to the router should be your first consideration.
Double shielded interconnects are highly desirable.
If you still have RFI (Radio Frequency Interference) then go with shielded power cables.
What difference do power cables make?
I’m considering a purchase (about $1000) that will include a power distribution box and a couple of very good cables to service my power amp and subwoofer..
For those who have upgraded power cables, how you would describe the sound quality difference in your system?
Do you feel that it was worth the additional investment?