Ethernet

@audioman58 said:

which btw digital is not grounded

But the chassis of equipment the shielded ethernet cable plugs into may be. I’ve read posts where a shielded ethernet cable caused a ground loop hum. (Had nothing to do the 4 twisted pairs of the cable.) My understanding the shield is connected at both ends of the cable to the ground metal shell of the RJ45 male connectors. Example of a shielded Cat6a RJ45 plug

If the equipment manufacturer didn’t install a RJ45 jack that is a grounding type, bonded to chassis, then a path to chassis ground is not provided.

FWIW a shield, Faraday cage, does not need to be grounded to work.YMMV

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I tried a blue jeans cable to compare it to my $1000 cable and I sent the blue jeans back once it got broken in (100 hours). I’m sure it would be a step up to cheap/free cables but lifeless/dull sounding compared to better cables.

When you get an Ethernet cable, it’s not the speed that you need, it’s the better terminations that the better cables give you. Audio throughput is small, remember a cd player spins at an avg 300 rpm with small data output. A cat5e cable would be fine even up to dsd. I have a top of the line audioquest Ethernet cable

As said get a blue Jeans cat6 cable. They are certified, that is really all you care about. A lot of cheap cables are not terminated properly. I used to make my own cables, still have the stock and tools. It takes a lot of practice to get all the little wires correct. 

If you are going to order a cable, get one from a computer store, get a name brand, like Belkin, or something. They will not be "cheap" but also not expensive. A 6ft cat6 cable should be around $20.

I have very good results with Supra CAT 8+ ETHERNET cable. The cable Made In Sweden, very good balance between quality and price. Different lengths available at eBay. 

In your home, most affordable switches and ports support 1GigE, as do cable modems and routers.  That's not to say the Internet provider will offer you that much bandwidth.  That's Cat 5e.  It's also probably 2x or more what you get from outside.  100 Mbit/s was also something like 10x more than what 96k/24 bit audio required. 

So, it's all overkill.  However, it's best to know your equipment's rated throughput, as bad/slow cables can cause your gear to keep switching speeds and/or disconnect.  So if your gear is 1GigE stick to 5e or better.  Use Cat 6 if your switches/ports support 10GigE.  Again, massive overkill for audio/video.