Hi Hector,

Just to confirm, are you talking about having a network switch with galvanic isolation built in? If so, do you know if such switches exist?

I'm now wondering where isolation is best applied, and if it ideally needs to be applied in several locations in the signal chain. Gut feel suggests it would help to nail the noise earlier in the chain, rather than in the last few cm before the ID4x card. I'll experiment a bit with putting the GISO in different places, although I think I may need a couple of units to get any decisive results. I also wonder if multiple units might bring some negative impact.

I may follow Cujo's lead and try in some good quality linear PSUs on the Wi-Fi router and switch to cut out some of the nasty 500KHz noise there. PSUs share their earth connections with the units they power and, consequently with the earth used in Ethernet cable. Each side of each balanced pair carries a signal that is referenced to earth, so this is the perfect place to inject degrading noise.

Of course, there's also the Wi-Fi router, in my case, sitting half a metre from the switch, happily banging out RF at 2.4GHz and 5GHz. RF loves push fit connection points as a place to work its way into a signal chain. Maybe I should build a Faraday cage and put the switch inside that ... :-)

Dave

808v5, MD600 & DSP7200.1
Dedicated audio mains supply