Are there any?
For years, I owned a residential A/V company, and we put in a ton of Sonos. Forever we begged them to put 4 zones in a single box, for rack mounting and connecting to a multichannel amplifier. They of course never did and now have much bigger problems.
But apart from the NAD BluOS piece (which has its detractors) is there anything out there in terms of multiple zones?
There’s the Monitor Audio IMS-4 which is listed as Roon Ready. But looking at the back panel it’s looks suspiciously like a re-badged NAD CI–580-v2.
There’s a few sellers on Etsy selling 19" rack mounts with 3D printed faceplates for WiiM Amps and 3 x HiFiBerry Amps. The HiFiBerry Amp 100 boards in that rack would I make a nice low-cost solution for multiple zones of ceiling speakers.
This company has a 2U rack for a 2 x WiiM Ultras.
Penn Elcom also have a wide range of 19" custom faceplates, but it doesn’t look like they have one for any Roon Ready devices like the WiiM yet, but might be worth keeping an eye out there or dropping them an email.
Are you looking for just a multi-zone endpoint / streamer, or amps as well?
There is also this device.
A core + 4 zones
It looks like WiiM also have their own rack mountable CI range available exclusively to CI installers.
It has also occurred to me to try multiple usb DAC plugged into a ROCK.
Are you sure those would work with Roon?
I don’t think it supports roon - at least as far as I can tell.
May just be “yet”!
Love Yamaha, but it’s not Roon Ready or compatible from what I can tell.
And I love the form factor; that’s exactly what I was imagining.
I’m not seeing anything at their site? Is it even real?
Who knows - but the web presence doesn’t inspire confidence!
I wonder if there’s an easy way to rack mount a few WiiM amp pros the way some studios do with Mac mini/studios.
Seems there is Pure Theatre 2U Rack Mount | WiiM AMP + ULTRA
Yes, that’s one of the racks I linked to above, that’s probably the easiest solution, plus easy to swap them out if you ever need to.
Not sure about the WiiM CI units supporting Roon, it doesn’t look like any of the product have even made it out into the real world yet. Shame as the WiiM CI Mod S4 looks like it would fit the bill - assuming it existed and was Roon Ready 
While the 4 x Zone BlueOS units fit the bill physically, there been a few reports of them not being up to the task. My guess is they probably get less regular updates than the consumer units too.
For a low cost solution, this 3D printed rack for the the HiFiBerry Amps makes a neat solution, install HiFiBerryOS or Ropieee on each RPi and you have 6 channels of power in a single 2U rack. But probably a bit too DIY / Heath Robinson for a commercial install, but for someone wanting to power a bunch of ceiling / patio speakers in their own house it’s a potential solution.
Well, it supports Airplay 2. I’ve connected a WiiM Pro to the line input. So not Roon Ready.
My gut feeling is this range looks a bit like vapourware with no more than a few demo units previewed at trade shows, but the spec sheet with a WiiM logo on it lists Roon as one of the supported protocols.
If anyone knows more about this range, or is inclined to reach out to WiiM or Henley Audio / Origin it would be interesting and I expect useful to other to post back here with what you find out.
I have a Whirlwind 4 zone (I don’t use the Core functionality) and it works great. Super easy to set up and configure. Marry it with an 8 channel, 4 zone amp and it makes a great multi-room system. Not sure what happened to their website. They recently did a repair for me, so I’m pretty sure they are still in business. You might want to try contacting Small Green Computer, as I think they did the build for this unit. Not sure why it never took off, other than it is price.
MarantzM4 is ROON ready and works superbly in my set up.
Really interesting, had missed this!
That looks perfectđź‘Ś as a Roon Ready distribution amp.
Does it come with 19” rack ears? Although I guess it’s heavy enough not to move too much on a generic rack shelf.
Yes has ears and isn’t too heavy for my rack …
Am I missing something? I’m at Marantz site for the Model M4, and while it indicates it has HEOS, I see no mention of Roon or being Roon-ready?
Sorry - my mistake - I now see “Roon Ready” on their site.
But can someone explain what this means? If I connect this to my LAN via Ethernet and turn it on, do 4 new zones appear in Roon under “Audio” in Setup?
Or? Thanks in advance, and am trying to understand what’s out there for replacing rack-based, multizone Sonos systems.