Thanks, Darren. I wish I could take that accolade, but others here definitely discovered (and, thankfully, pointed me to) the ENO before I did!
For various reasons, I haven't been able to try the ENO with my 818 (it needs to go back for a service), however I would expect it to respond even better on the 818 than on the music player that precedes it (which also drives my Stax setup). That caveat aside, the SOtM switch with their master clock, cap upgrades etc and the Innuos PhoenixNet are the best switches I've heard in production so far. The Innuos makes a better case for itself as it has twin independent power supplies and, what is meant to be, a better clock included in the price (you have to add £500 to the cost of the SOtM to get their single rail SMPS).
The ENO improves on these two switches dramatically, but the combination with a decent switch delivers so much more than it can on its own. If you don't have a high-end switch, I think you'll hear a terrific difference with the ENO. If you do have a high-end switch, it sounds fantastic!
PS Ethernet cables is another kettle of fish, for the run into the ENO, I would recommend their own silver cable. For other runs, the best I've tried so far is the AudioQuest Diamond (which I use for the SpeakerLink connections), but pricing is not for the faint of heart! You can find them on eBay, but make sure they are coming from someone reputable as there are lots of clones out there. I'm in the process of making up my mind on some other Vertere cables, but I don't feel I'm in a position to comment just yet.
Unfortunately, I've never tried Shunyata's ethernet cables, the relationship with my dealer broke down after waiting months (now well over a year) to trial a cable I knew they had in stock (after buying quite a few cables, I might add). I'm likely to rebuild my relationship with Shunyata with another dealer as Shunyata's own support is literally second to none (I sincerely mean this, I have never come across a company that bends over backwards to help in the way they do).