Yes, I was thinking of switches etc. I’ve been looking into whether my ZTE 4G hub could be improved by a different 12v power supply. That seems to be one of the latest trends.
Just to echo TAPP’s thanks. You have a way of making impenetrable teccy stuff seem intelligible (or almost intelligible) to the completely clueless like myself.
Electricity prices are falling, the cap is reducing.
So say for example someone had a spare managed Cisco 3650 (previously used to improve 272) and to scratch an itch might try and reintroduce with a Ubiquiti Flex mini powered by POE (30 quid, why not….) 
In this hypothetical situation all lounge network devices (NAS, NDX2, SkyQ) would currently be connected directly to ISP hub with CatSnake cabling.
I am guessing the way ahead here would be to daisy chain from hub to 3650 to Flex for NDX2 then have the long cable run to the device, with NAS/Sky still connected to ISP hub, or maybe NAS to Cisco?
Our previous experiments with NDX2 and separate DAC didn’t find any SQ difference with and without switch, but maybe POE is the secret sauce 
I don’t think you’ll find a difference. An ndx2 with seperate DAC effectively eliminates any considerations on the network other than it needs to provide reliable Ethernet and connected services…. At least that is what I found as well.
So it then becomes more about having physical distance (electro magnetic distance) between relatively electrically noisy network equipment and sensitive audio replay equipment. A PoE powered switch should be a step in the right direction here… but this is then not about networking, just local electrical environment.
In that case we won’t bother, since the hub is already well away from NDX2.