@garebear the purpose the cable will serve in your setup is an interface between an SACD transport and a DAC.
1. It’s most likely a really short run.
2. You don’t have to deal with garbage associated with routers, switches and the wall wart power supplies that inject noise. Your connection is actually as clean as it can be.
Cat6, 7 or 8 should all be compatible. Comes down to how much you’re looking to spend to stop wondering if you could have done better. And if you hear a significant difference between the $360 Purist and a $3,000 Shunyata.
Also, from what I’m reading, GG45 connectors are comparable with RJ45.