Audiophile network switches

Thanks, I think a diagram helps to get the information across in an easily understood way.

I am no fan of fibre in terms of sound quality and indeed I would be inclined to try your suggestion of replacing the fibre link by using a 20m CAT6A UTP direct from the router to the PhoenixNET except that my router only has one ethernet output and that goes to the first Cisco. What I might try though is first doing the Cat6A between router and PhoenixNET and then compare that with using the Cat6A between the two Cisco switches.

The Wi-Fi to iPad is not intentionally behind the fibre isolation (and which I am not convinced by in any event) but rather the router is the only means I have of Wi-Fi communication between the iPad and the network.