Agear, I tried the Apprentices without the cups against the bottom of components and with them. Having them was somewhat better. I do also use them on my hardwood floors. I did try IsoClean feet instead of the Star Sound cups and heard no difference. I would imagine that not using the cups would be better on carpet.
I don't know whether it is the HFC ics, speaker wires, pcs, or the WGPC, the Star Sound Apprentices, the Koda K 10 preamp, or even the new Empirical Audio Legacy music server, but I'm playing louder, enjoying it more, and have had few complaints about the music being too loud.