Listening right now to the Z1R with the Sony-branded Kimber cable (1.2m length terminated with 3.5mm mini), switching back and forth with the stock cable...
For the record, I'm not a big believer in high-end cables vs decent stock cables of the same material. I can't tell a difference except if the stock cable is bad to begin with. I do believe in different signatures between cables of different materials, however. So with that in mind, I was expecting at most perhaps more bass and mids weight with some rolling off of the highs and some darkening overall, due to the full copper of the Kimber vs the silver plated copper of the stock cable...
Well, so far I don't notice any darkening or rolling of the highs, so that's unexpectedly nice. There is definitely slightly more body to the mids and bass. Think it might have more to do with the 8-4 wiring design than the materials, honestly.
I'd heard some people talk about microphonics issues, but mine is pretty decent. Definitely there if I tap or play with the cable, and more so overall when compared to the stock, but just sitting and typing they are silent. It's a weighty cable, and tends to stay where it rests. So no real issues there for me.
Side by side with the $700+ Kimber Axios cable that my buddy has, it's definitely the same cable, albeit with a plastic/resin Sony branded splitter vs the wood splitter on the Axios, and metal Sony branded connectors. So I guess it's a bargain? If one can call saving $450 by only paying $250 for $6 worth of materials a "bargain", ha ha. I'll go with "slightly less idiotic".
At any rate, I'd place them in the "minor upgrade" category vs "sidegrade", so better than I was expecting... I'm pleasantly surprised. Again, nothing shocking, but hey, a minor upgrade to something already stellar is always nice. Whether or not it's worth the $229 MSRP is up to you. I paid $250 and change after tax with Amazon, just for the return policy, but I think I'll keep them. You can get them off the bay for just under $200, but you'll wait for them to ship standard mail from Korea or Japan...