Audio Grade Ethernet Cable

sns

... how do we eliminate, or at least diminish this pollution source? We locate modem and router close to audio system ...

How does that diminish the "pollution source?" It only puts these noisy components closer to your audio system. 

... modem and router powered via lps ... disable wifi on router in order to eliminate contamination via rfi ...

You can just as easily implement those remedies while also keeping your network components distant from your audio system.

And that’s what I don’t understand: What is the advantage of locating your network components physically close to your audio system? The only benefit I can imagine is that it reduces the length of the one ethernet or fiber cable that connects to the streamer. Please tell me what I've overlooked.

Any Ethernet cable is "audiophile grade" because they all simply transmit ones and zeros. The ones that claim to do that better are either lying or uneducated.

OP, if you follow advice to move the router far away and plug into a different circuit, I have an unused DH Labs ethernet cable which I think is 6M. Switched ISPs and the new company supplied a remote extender entering the floor under the rack holding streamer, which I plugged into line conditioner on audio circuit and switched to a shorter ethernet cable. No detectable increase in noise from prior setup. Anyhow you can have the 6M cable for the cost of shipping if you decide to go that way.

Repeating myself. How does putting modem and router close to audio system pollute if wifi disabled? Does a long ethernet cable connected to a switch or streamer magically reduce this noise? 

Now I'll agree the most optimal solution is likely an all fiber network, this requires not only the service but also fiber capable streamer. For cable service optical conversion can be a positive step, I do this myself, but this instituted specifically for my two streamer Roon setup, in other words post Roon Core streamer. 

So, going full optical requires both optical service provider and streamer with optical input. Cable service will require fiber conversion and not all conversion schemes created equal. So lets say we've done the fiber conversion for the cable service either at router or just post router, so issue of long LAN cable moot. Now we have the issue of AC supply/possible contamination of AC and wifi contamination of the optical router itself. Seems everyone agrees LPS is a good thing vs SMPS for streaming components. With modem (I also power this with lps) and router far away from audio setup I'm going to assume these will be powered via common house AC lines. Is the assumption quality of ac feeding the lps for these devices of no consequence? Can you be sure of this, or do you have evidence this is true? With my setup, modem and router, both lps connected to my power conditioner via dedicated AC lines. 

And we still have the issue of wifi contamination of the router itself and likely closely situated modem. Optical schemes aren't addressing this issue.  

My network solution can be both a tidy and 'clean' solution in that it may make fiber conversion unnecessary. Having a 'clean' or audio only network likely makes optical conversion a moot point, you've rid yourself of wif rifi contamination,  diminished self generated noise via lps, quality AC feed, add in very short runs of quality LAN cable.  And all this only requires relocation of ISP service port and a second router, such a small expenditure in order to hear for yourself the advantages of this setup.

I suppose I understand the resistance to even trying this scheme, assumptions and presumptions are inherent to our species. I can't count the number of times I've been told this and that can't possibly make a difference to sound quality, and I also can't count the number of times that's proven to be untrue. I've found that experience is the best teacher, and I'll continue to believe that. Try it you might just like it.
 

I should add the one thing I have yet to address is whether the amount of network traffic impacts streaming sound quality, my scheme doesn't address this. This is where the Dejitter Switch X managed switch comes in. With this managed switch a 'truly' segregated audio network is achieved. Switches don't have the constant pinging in order to locate devices on one's network, all this pinging migrates to the second or whole house router. There is some interesting discussion on this switch and the need for a 'clean' network over at youtube and I would expect at audiophilestyle forum.