Agreed. However if you accept that equipment is badly designed and faulty (contamination from TCP/IP communication is reaching the analog out) then a mere change of cable might influence things in an unpredictable manner.
This may be true for more analog components where vendors design and roll their own analog topologies, Ethernet is a different beast where you are only getting PHY’s from a handful of companies. These companies release these PHY’s with reference layouts that you need to use because they are there for SI, power efficiency, and meeting spec.
Out of 100 meter standard most pre-packaged solutions AFAIK of boutique cabling is 3, maybe 4 meters, with the majority being 1 or 2 meters as more the norm.
If they are all in spec cables, they are in spec. Even green Ethernet Switches that reduce TX / RX power is for 40 meter or less runs.
SI and power envelope isn’t an issue at 1-4 meters. If your connecting through structured wiring in the wall then that last 1-4 meters really isn’t going to matter much since you will only ever spec out to what is the weakest link regardless of how much is spent on a patch cable.
I think crap gear is going to perform equally bad with two same constructed, same length, spec passing Ethernet cables.
I am convinced that some anecdotal reports are pure placebo (result of parting with $700) effect but many others are actual equipment issues that happen to be identified or brought to a users attention when swapping out cables.
Do not underestimate the amount of badly built equipment out there. Manufacturers read the latest DAC chip instruction manual and throw a DAC together with a gorgeous looking faceplate and there you go. Analog audio designers are often challenged when faced with advanced digital circuitry, ethernet, USB, firmware etc. - the possibilities for overlooking error and contamination sources multiply in digital.
Thats fair. I’ve done enough installations with NAIM, Lumin, Oppo, TEAC, DM Holdings, now that those are the manufacturers I would recommend as having properly implemented gear.
Still the logic of my offer has been such that no one is willing to take me up on it.