Digital isolation between Ethernet hub and streamer

What I said originally was

near zero EMI and RFI pollution from it due to its proximity to the rest of my gear.

meaning it does not pollute my system. On its own it produces a good amount. I have to chew this for you?

Then you stated this

I tried measuring the effect of lifting my dustcover and surprised myself with the lack of attenuation of pink noise, compared with white noise

Well I have been measuring the effects of your removing your dust cover and my findings are there is definitely no attenuation of noise. My recommendation is - keep your dust cover on. Especially on your keyboard.

Audioman58 - thank you for your post. I have been streaming my music for over 8 years and I am amazed at the quality level I have already achieved in my two major stereo systems in my home.  I stumbled on a major audio upgrade by converting my incoming signal from Spectrum internet (average speed 200 Megbits per second over copper to my router) to fiber optics into anew router -  (at 550 Megbits per second ) . The audio quality improvement shocked me. More separation, lower noise floor, better soundstage, cleaner horns, etc. I feed my streamer/ dac via Ethernet cable. I just ordered the Smoothlan network filter and will insert it into my main stereo system in front of my LUMIN T2. I simplified my streamer/DAC journey by going with LUMIN - I run a T2 in my main system. I will happily report back as to if I hear improvements inthis system. Please note my LUMIN T 2 feeds my Krell 300i integrated amp which feed my Peter Gunned Maggie 1.6 customer speakers, with The Swarm sub woofers handling the bottom end. I think my system will be able to resolve any improvements that come from a better/cleaner incoming signal.

I have a longish run of ethernet cable (50ft) to my DAC/streamer from my router, so I thought I’d see what the ifi lan ipurifier pro could do for me. If anything. First though, I connected it between my 8K tv and router that sits right next to it, to see if there would be any visible benefit. Re-watching the final season of Dexter I had just watched, there was a nuanced difference in color naturalization and better edge definitions but not huge, just nice. The sound difference was more noticeable. Dialogue that was fine before was more detailed and things like actors breaths that had been inaudible before were delineated. Music had more punch and delineation too. Then I moved the ifi lan ipurifier pro to my main rig right before my Bricasti M1 DAC/streamer. I switched back and forth on Natalie Merchant’s song Carnival, with and without the ifi lan ipurifier pro. With it, the conga drums have much more noticeable timbre than without, instrumentals are better separated and the whole presentation is just slightly better. I’ll take that level of improvement all day for under $300! Also, I missed the the ifi lan ipurifier pro on my tv, so I bought a second one. These tests were with the really cheesy power supply the ifi lan ipurifier pro comes with. I have since ordered their high end power supplies. I’ll let you know if I hear any difference with them after I test them out. I really don’t get the naysayers who have not tried a piece of technology in their system but feel qualified to weigh in negatively. The ifi lan ipurifier pro makes a clearly positive difference that both I and my non-audiophile wife can see and hear in our systems. Each system is different, and your experience may be different than mine, but basing opinion on first hand experience is key.