Anyone have any experience with the Tunami GPX-R ?

I own two GPX-R (white plugs; for power distributor and integrated amp) and I am waiting for a third one for my digital source (instead of the GPX, red plugs).

GPX is a very dynamic cable with a strong mid-bass but it hides some microdetails in the higher frequencies, resulting a "dark", "warm" sound.
Recommended for systems weak in the bass and/or too bright/harsh on the top.

GPX-R shows even better dynamics, great bass strenght and definition, real neutrality with very good details, focus and soundstage, an almost universal cable, recommended for all systems.

The difference you mention between GPX and GPX-R is interesting. It is the same exact cable. The only difference is the connectors.