Ethernet cable for Streaming

CAT 8 has the best shielding and I believe maybe tighter twists - read about it here.You can also make the bulk of your run using fiber for a small cost.  Two converters like these and 45-50 feet of fiber with very short CAT 8 runs at either end.
I run 45 feet of fiber and also have 45 feet of CAT 8 in the same run that I was using before the fiber.  I have compared directly and hear virtually no difference - maybe a touch smoother with the fiber, but I could be imagining it. 

That is how I started, with a short run of fiber at the end.  Consider the CAT cables are susceptible to picking up EMI/RFI and the fiber is not.  Why not just run the whole 15M as fiber with a very short CAT cable of your choosing from the second converter to your streamer/server?  That is how I ended up - with the long run in fiber.  Consider buying a LPS for (at least) the last converter instead of using the wall wart.  Some report benefits from using LPSs on both converters and the router, which is what I have done. Also, make sure you purchase the correct fiber cable that matches the connections on whichever converters you purchase.  Good luck.