ADVICE NEEDED:
How much would you spend on a rug in percentage terms against source, amp, speakers and cabling?
I've got wool but my mate swears by acrylic or shagpile. There are some esoteric ones like leather but I think that's just snake oil, and the bang for buck upgrade beyond a certain point is not worth it.
Also size does make a difference IMHO.
The backing of the rug has to be right Hessian too, and the thicker the better to add shielding from RFI.
A red one looks good with my system.
I found a bigger soundstage, more musicality, no fatigue and tauter bass and indeed, across the frequency range. Smooth, sweet treble and articulate. Natural, spacious and airy.
Check out: http://www.rugmerchant.co.uk/index.php