“would adding such a device yield an audible improvement?”
@pdurham2
The only sure way to know is by auditioning one in your system. You do have a very nice system to decipher subtle changes from tweaks like Ethernet switch and/or passive noise filters. I recommend connecting your NUC and Lumin through a switch like LHY SW-8 and further adding a Network Acoustic ENO filter in-between switch and Lumin.
Please ignore the close minded folks!
https://www.networkacoustics.com/shop/eno-streaming-system/