Ethernet

25ft of Cat5/6 cable is just fine, don't have to worry about it until over 200ft. Would stick with C5/6 cable, no need for anything higher. C7/8 cable is just rated for higher frequency for higher bandwidth. You can not take any advantage for it. C6 is 10gb rated, streaming music takes 2mb. There is plenty of headroom! 

Remember this is a digital cable, it carries packets, not wave form analog signal. EMI/RFI does not affect packet transfer unless it's really bad, like really, really bad.

Best practice for any network is fewest hops as possible, fewest conversions as possible. 

Any consumer cheap mesh setups are garbage, they limit transfer speeds, they have poor handoff, get overwhelmed very easily. You are far better off just getting another higher end router and extending your current network. 

If you have a cable modem, get rid of the rented modem, it's a Toal PIECE OF POO! Just upgrading that will yield benefits everywhere. 

@fastfreight I agree that front end tweaks and power cords can make a difference.  My thesis is that through engineering they should not!  Off the shelf components would appear to be available to solve the problems.

@drmuso 

I agree with what you posted.   One point -- depending on the design of the streamer, it "may" help sound quality to "turn off" the wifi reciever on the streamer and use an ethernet cable.  

When I first got my N130, I tried the same thing.  I bought a long Cat8 Amazon cable. Yes it works, but the cable doesn’t have a lot of insulation and occasionally picked up noise.  I ended up buying a Netgear Powerline 2000 +extra outlet on Amazon.  Used it for years.

Yes ,but several factors , go to blue jeans cable and buy Beldons best Ethernet cable ,your rougher needs to have a LPS power supply ,that $5 wall wart just ads noise , then you need a decent quality Ethernet hub  LHY 6  perfect for you 

nothing at under $600 has. Precision clock ,LPS power supply and low noise regulstors, the cheapo $20 are junk and just make more noise ,your end point 

Ethernet cable to your dac is most important  depending on budget,

Wireworld make a decent one for under $250 then you will hear nice improvements