I've had a Network Audio Muon on loan from a friend for over a week now. I tried it at the audio end, between my EtherRegen and exaSound PlayPoint renderer, playing files from my NAS. The difference was so subtle that it took me a few days to figure out what it was doing to the sound. In the end I determined it was slightly veiled and rounded the transients, smoothing the sound. I must emphasize, this was extremely subtle. Obviously not a worthwhile purchase for me. Maybe it would work for someone with an overly bright system, but the cost is daunting.
I had been disappointed with the sound of Qobuz, so I tried to improve it by inserting various combinations of three ethernet filters (Muon, LAN iSilencer and eBay filter), alone and in pairs, upstream and downstream from my router. Adding the Muon alone, between my router and switch was a clear improvement. Fortunately, I don't need to add an expensive Muon. I was able to achieve the same level of performance achieved with the Muon by inserting the eBay filter ahead of the router, and the iSilencer upstream of the N8 switch.
I have been listening to Qobuz with no thought that it is lacking. Qobuz is very close to the sound quality from my NAS, close enough that I can only tell which is playing by direct comparison.
Muon: highly detailed, bass a bit imprecise, smooths the sound, voluminous soundstage
LAN iSilencer: highly detailed, bright sound, emphasizes sibilants, tight but light bass range, shallow soundstage (upfront presentation)
eBay filter: lacks microdetail, warm & smooth highs, big bass but a bit flabby, good soundstage
https://www.ebay.ca/itm/232318518946
Both filters, used together in the right location are an awesome value!