Thats what I was thinking, but even so, it is a weird product. First, Ethernet does not have a ground wire; and ground is the biggest source of electrical inte

Thats what I was thinking, but even so, it is a weird product. First, Ethernet does not have a ground wire; and ground is the biggest source of electrical interference for analog audio. Second, the Ethernet switch is a really weird place to try an address this. If this is your concern, I assume that you hold every peripheral that plugs into your computer to at least the same standards (especially almost everything else you might plug into it, as most connections attach directly to ground). You also need to deal with all of the noise that components inside your computer can generate. If electrical interference in your analog components are a concern, you are better off spending your money closer to the analog circuit. An electrically isolated sound card with a digital input 100% solves any concern about analog noise in the rest of the system [0]. [0] Unless the noise is so bad that it interferes with the digital computation.