Which personal confuser for ultra high end audio, MAC, PC, notebook, tablet or desktop?

...any cable that is conducting high speed digital signals, such as an ethernet cable, and that is located in physical proximity to the audio system (e.g., in the same room), can radiate or couple RFI into the audio system. And in addition, noise conducted into the destination component via the cable could to some degree (depending on the specific design) conceivably couple around the ethernet interface circuitry and into other circuitry within that component that is more directly involved in processing the audio. Including circuitry that may be sensitive to noise-induced jitter.

None of this necessarily means, however, that an ethernet cable costing hundreds or thousands of dollars would be any more beneficial than an upgrade to a very modestly priced cable. You may wish to consider experimenting with inexpensive shielded ethernet cables, as member Bryoncunningham described doing in this thread, with significant sonic benefit resulting. (I consider him to be a particularly astute and perceptive listener, btw, and one who is very thorough in his approaches to evaluating tweaks and optimizing his system. Unfortunately, though, he hasn’t been posting here in recent times). See the posts in that thread dated on and around 2-16-12. Inexpensive ethernet cables are commonly unshielded, but good quality shielded cables are also readily available at low prices.

As an electrical engineer having extensive experience designing high speed digital, analog, A/D converter, and D/A converter circuits (not for audio), I don’t find the reported differences to be either surprising or mysterious. And I consider them to be well within the bounds of established science and engineering.

Most likely what is happening is that differences in the characteristics of the cables, such as bandwidth, shielding, and even how the pairs of conductors that carry the differential signals are twisted, are affecting the amplitude and spectral characteristics of electrical noise and/or RFI that finds its way via unintended pathways to unintended circuit points "downstream" of the ethernet interface in the receiving device. "Unintended circuit points" may include the D/A circuit itself, resulting in jitter, and/or analog circuit points further downstream in the component or system, where audible frequencies may be affected by noise that is at RF frequencies via effects such as intermodulation or AM demodulation.

"Unintended pathways" may include, among other possibilities, grounds within the receiving device, parasitic capacitances, coupling that may occur into AC power wiring, and the air.

What can be expected regarding such effects, however, is that they will be highly system dependent, and will not have a great deal of predictability.