It’s just appearance. It’s stated here: https://www.networkacoustics.com/shop/muon-pro-ethernet-filter/
Thank you! I just need to read it 
I felt better already.
Haha I know this situation very well when you got so shocked, wondering that your visual system nearly halts
Though Network Acoustics has had some very good upgrades like their Muon2 cables and let’s see if they come up with something around High End in Munich maybe.
Didn’t know about that, Donald. Anyway I like the two ports version, more practical behind the rack IMO. And you can experiment with other cables!
Now I’m a little disappointed. 
When I ordered my Muon Pro, I specifically asked whether the Muon Pro would also get an upgrade and have the ports on one side like the ENO 2. I was assured that this wasn’t planned. Now my wish has been realized. The new model does appear to have a metal casing ?
Seems to be unplanned/supply chain related…from the web site:
“PRODUCT ANNOUNCEMENT: Due to issues with our supply chain we have reconfigured the muon pro Ethernet Filter. Please Note this is not an upgrade and the sonic performance of the new version is identical to the outgoing model. Due to the additional weight of the new enclosure, we have implemented the “in” and “out” RJ45 socket configuration used in the eno2 Filter. The muon pro Ethernet Filter now includes a 0.75m muon pro Streaming Cable as standard.”
No it’s not a metal casing. The new ENO2 has one.
Is anyone using two Muon Pros, or Muon Pro + Eno/Eno2 in their system due to increased benefit? I’m debating whether to bother trying. I have two switches - M12 Gold and NA tempus - with the Muon Pro right before the Taiko streamer.
Ooh, very nice.
Yes I am using a ENO2 streaming system and a Muon Pro streaming system. Adding the ENO2 (between ISP modem and switch in my case) further improved things. So definitely recommended.
So three weeks ago I apparently was gifted a Stealth Audio Black Magic Ethernet/LAN V21 Cat Ultra 8 cable. I placed it between my BACCH-SP and its MUON Pro, backwards. As always I do not believe the cable has changed the sound one way or another.
It’s a blessing and a curse this affliction I have. I do not seem to hear Network changes involving cables and switches. I do hear MUON Pros and to a lessor extent, the Schnerzinger Grid Protector. I think I am going to unplug it and take it to the attic. See if I miss it. These days I just seem easy to please with my gear. Then I go to my friends house, he with the single best system ever, and I see what that is like and it’s so very much it’s own thing. As long as I can visit there I can soldier on with my odd setup.
I’d love to say the cable changed my world, but it seemed nice even before the cable arrived.
Maybe you need the version with the tuning ring! Lol
It is a blessing for sure; the money you saved on network cables and switches is enough to add two more Stealth power cords. There is something true about this statement since I also heard less difference after two Gryphons are in the system. Now, a different ethernet cable and a different switch just sounded different, but the system simply sounds great regardless of what cables I am using. Of course, I still hear a difference from switches, but the urge to spend more on a more expensive switch has diminished greatly. Like I say, the system sounds great with a decent switch and network cables!
The only cable that I still hear meaningful difference is power cable. I have always heard bigger difference from PC than IC or SC, and PC mix is still crucial. For example, I like AQ Dragon on LHY SW-10 pro more than any other PC (even Stealth), the combo is a perfect match. On the other hand, Takshaka PC on DS MK2 sounds better than AQ Dragon. But, after Gryphon D333 was added, I heard less of a difference than before. Also, I cannot hear much difference from the tuning rings anymore (whether they are DIY 3M or Stealth rings). I remember I could hear clearly with an inch here and there adjustment, but now I could not.
Once the system reaches a certain point, the SQ supremacy from components governs more than cables and tweaks, I believe. Although it is possible that my hearing is not as good as now from a few years ago.