Good on you for testing but alas it is the well known problem of Focusrite and Linux rearing it’s ugly
I have the 18i20 Gen3 and tried everything already lol
Looking forward to your M4 experience update
Keep Ubuntu locked and loaded for that test 
Now he says it’s already been tried on the 18i20 G3!!
Yes, the Ubuntu/RooBridge is on a spare RP4, so it’s all ready for the M4 arrival. Shame that the 18i20 can’t work (yet) as it’s got twin headphone outs, which would suit my wife and I for listening sessions when our little boy is asleep.
True, the RME ADI-2 DAC has phones and IEM outs, but balancing their levels is virtually impossible without the independent gain knobs of the Scarlett. May have to look into a Fireface UFX + instead.
Lol I said I have it and tried to (strongly) hint early on this is a well known Focusrite problem
I linked 2 threads and could have linked 10 more 
And therein lies my eternal desire to make things work, by blocking out the negative!
You did hint and you did link, but I misread, possibly deliberately, that Ubuntu/RooBridge was a solution for Focusrite, whereas it seems to be a solution for MotU only, among the ‘pro’ audio interface manufacturers.
My bad and my evening partially wasted. However, got to listen to some old Nils Frahm favs again, so not a total waste.
1 Like
All good.
In those threads I linked are the 2 guys that have worked out the potential fix.
They are working on bringing the fix to the mainline kernel one day.
So the day there is a fix you will hear about it from the guys doing the fix in those threads I linked… You won’t hear about it from anyone here in this Roon thread. That was the point of me linkin those
It will take a while because they are busy pro audio guys like you and doing the Linux fix in their spare time
It needs fixing. So it wasn’t me being negative. No amount of positive vibes will help
Correct those other guys that helped in this thread don’t have a Focusrite
Hopefully your M4 works out the gate
As I mentioned , someone has made an effort to make Motus play nice with Linux with latest kernels. Could be Motu themselves or a smart user has done the work
Motu and RME are the exceptions , not the rule, when it comes to Linux with pro interfaces, unfortunately. Especially with multichannel… which doesn’t affect you though
Could you just add a headphone amp to the ADI-2?
So you and wife have seperate volume knobs
A seperate headamp thats cheaper than ADI-2 of course. Otherwise would be better getting a 2nd ADI-2
I could test with my RME and seperate headamp and report back
Lovely little setup you have there.
Right, the M4 arrived today, so time to report on my experiences:
The M4 hooks up and powers up easily enough to and RPi, is seen by Roon and is able to be enabled in the Device Setup screen.
However, no audio is playable via the M4. This is the same regardless of Ubuntu or RoPieee. I tried both the included type A to C cable and a known ‘good’ USB 3 type C to A adapter.
Audio does play back from a MacBook when hooked up using the same cable, so I have to presume that it’s another instance of class compliance not being fully implemented by MotU.
I was rather trying to keep the box count down by incorporating the Focusrite with it’s twin headphone outs, but I think it’s going to be a two box solution now.
EDIT
Seeing as how others have got the M4 working as well as the Ultralight Mk5, I’ve just ordered a new SS10 cable (A to C) to see if the cable is the limiting factor. Initial impression though of the M4 through my MBP to Dan Clarke Æon Flow closed cans is not stunning. I think I’ve been spoiled by my RME!!
Are you sure about the M4?
I haven’t seen.
Yes, see here:
Specifically, under conclusions at the end, the author says that it is class compliant, so working in Linux.
Cable should drop today, so I can test tonight.
Ok, so cable came (Amazon Basics certified USB SS10 3.1 Gen2, type A to C) and I’ve had a chance to try it with the Ubuntu RPi to the M4 and also a RoPieee to M4.
With the Ubuntu, absolutely nada - Roon ‘sees’ the DAC and plays files, but nothing shows on the meters of the M4.
With the RoPieee however, you get low level noise on channels 1 & 2, despite there being nothing other than the USB C plugged in the back. This is able to be fed to the outs and heard as low white noise.
I’ve wasted enough time now on an interface which is ok, but not brilliant and certainly not a patch on RME quality. It’ll be going back as it’s clearly not fully ‘class compliant’.
1 Like
Update:
Installed Ubuntu Server 21.04 on my RPi together with Roon Bridge (a lot of faffing with Terminal required and several little package installs required) and the Focusrite Scarlett 18i20 is now SILENT
No clicks, no pops or vinyl effect, just inky blackness.
Not tried the Motu M4 on the end of the cable yet (BTW, 18i20 is hooked up to USB 3 from RPi using a SS10 Amazon Basics cable, as previously described).
The kernel installed with server is now:
Linux 5.11.0-1019-raspi
So it seems the 5.11 update is the key.
So, twin, individually controllable headphone outs now, from a single U rack. Chuffed!
1 Like
Very nice ! I think I’m still running 5.10
I’ll have to dig into what has been added to 5.11 specifically , out of curiosity
Something important it seems
Maybe a turning point for pro audio interfaces and Linux
Curious to hear if M4 also now works
Ok, so plugging the M4 in now produces an output on channels 1 & 2 and what I presume to be digital noise at 0dB is showing on the 3 & 4 meters.
Audio output via headphones is clean and powerful, despite bus power, so I think I may well keep and try the new kernel due shortly to see if that clear up the spurious 3 & 4 noise issue.
I have been suggesting 21.04, and 21.10 on multiple threads.
The later kernels seem to address many compatibility issues.
Its reassuring Linux is heading the right direction.
IMO Linux is the best platform for sound, and endless in integration and control integrations.
I just wish Roon would get the Kernels updated, in Rock (But its nothing a Ubuntu server install can’t address).
I believe this is a Roon/Kernel issue.
There is a similar thread on this here; where I have been quite active.
Later kernels (Like Beta Ubuntu 21.10, Kernel 5,14 I believe) fixed the unused channel issue for my Motu MK5. This was with a direct USB connection to my Roon server.
However If I moved back to an endpoint strategy using a ubuntu/roon RPI4 bridge endpoint (Running Kernel 5.11 for instance) the noise returned on those 9-10 channels. In my case I believe this has something to do with the way Roon addresses unused channels (I.e. over 8). Not sure how it would apply to a stereo situation.
In the end I proved the Motu MK5 works fine on the later Kernels, with direct USB connection to the Roon server.
However in the end I actually went back to Roon Rock (for my server), and RPI4/Ubuntu on the endpoint and simply muted channel 9-10. But its good to know Ubuntu 21.10 server beta was perfect.
I’ll make the jump to 21.10 (Kernel 5.15) fully on both server and RPI endpoint once its officially released on the 14th of Oct.
I understand you are using a stereo 2 channel setup, but the issues are similar.
So, I sold the M4 in the end - the headphone output wasn’t beefy enough to drive my Dan Clarke Audio Æon Flow cans and the unit just felt cheap to be honest - quite light and very hollow sounding.
I’ve now got an RME ADI-2 FS R BE - chalk and cheese, but then it should be as it’s 7x the price!
1 Like