Makes sense from what I’ve learnt from John Swenson and Rob Watts.
Shielded ethernet cables that have their shield connected to ground can provide a path for ground and leakage currents. UTP ethernet cables break this loop (they block most of the leakage currents) - depending on what’s connected upstream and downstream and what ‘loop/s’ are formed.
Leakage currents through the cables cause them to act as an RF antenna.
According to Rob Watts, the more detailed sound is often mistaken for what’s actually more RFI while the warmer/darker sound is usually the result of less RFI.
From some of Rob Watts (Chord) public postings:
“the warmer, smoother or softer sounding is the more transparent, as the mechanism for changing the sound is RF noise creating noise floor modulation - and more noise modulation always sounds brighter. Moreover, it’s very easy to confuse a bright sound with more transparency.”
Some other learnings from Rob on RFI:
“no ground loops, so no current flow into the ground planes, then no RF noise pick-up in the DAC and so no problem…”
“As to external RF, it only matters if there is a ground loop, so battery operation should mean no currents flowing into the DAC ground plane…”
“We need current through the ground plane to set up voltages - and it is these voltages that the analogue electronics pick up. So no current, no voltage on the ground plane, no pick-up… The common mode noise, won’t affect the analogue electronics at all.”
So I guess these are some of the extra benefits of blocking ground loops and leakage current loops, via the DAC anyway. And how shielded ethernet cables feeding a DAC can potentially do harm, depending on what the DAC is connected to (i.e. how it forms part of a ‘loop’)
There’s plenty of his thoughts on RFI all over the Head-Fi forums: