Galvanic isolation revisited.

Interesting.

Ethernet is inherently galvanically isolated. The reason for this probably has to do with the long distances it is designed to cover. You can’t be transmitting a signal with different ground potential references very well, so there are isolation transformers on either end of every twisted pair in an Ethernet cable (PoE may be different).

What the EMO seem to do very well is add a LOT of protection against lightning/power surges breaking through, as well as low frequency (audio and power) attenuation.

I would totally want to put one of these between my cable modem and Wifi router at least to reduce the chance of lightning induced surges.

How much was it? And how did you purchase?

I bought it directly from Germany, somewhere around $80. Agree with you and originally had it before the switches. Had an Aha moment when sticking it right in front of the server. The system seemed suddenly 2-3 db louder and more resolving. Given the effect I think it was more likely some ground level noise than RFI but not sure

…and btw: while inherently galvanically isolated Ethernet benefits in a big way from the Etherregen‘s moat. Go figure.

Which EMO - like this, or this, also available here?

I use an EMO EN70HD

It seems Mouser is carrying some of them now, but those prices ... 😫

What I do like about them is they are taking the opposite approach of a lot of network surge protectors. From what I’ve been reading about lightning damage in Ethernet networks, the problem seems to be that lightning finds too easy of a path to ground, and surge protectors with ground connections want to make it even easier. When the surge protector trips, a huge current flows and anything in that path is toast.

These do the opposite and add ~ 6kV extra isolation with each isolator. A really good idea right after your cable modem. OTOH, at these prices using a fiber optic adapter ($60 for 2 + cable)  to create an air gap is going to become very affordable.

Do you have a link to where you purchased it?

While I've not tried the EMO, in my comparisons optical has provided lower noise floor than a number of ethernet configurations I've tried. Optical is only solution that provides 100% galvanic isoloation, certainly not as many choices in equipment as ethernet.

OTOH, at these prices using a fiber optic adapter ($60 for 2 + cable)  to create an air gap is going to become very affordable.

That is what I use, with 45 feet of fiber from my router to the network switch at my system and it seems to work and sound great.  Of course I also use the Bonn N8 switch, a GigaFOILv4-INLINE Ethernet Filter, and the Network Acoustics ENO Ethernet filter and Streaming Cable.  I do not use anything on the USB cable from my server to DAC but the server uses the pricy JCAT USB Card XE, and my USB cable run is only 0.8M.

@mitch2 I use the fiber converter to create a surge DMZ.  It separates my cable router from my internal Ethernet devices.  Otherwise my Pi / Roon streamer is just going to have to cope with the network as it is.