I have had the same issue with my MOTU M2....
I am using a MacBook Pro with M1 Pro processor along with the motu M2....
I checked the many possible causes for this issue... I tried a different USB cable (which does make a difference by the way... and a cheap cable will make things worse.... but if you use the cable supplied by Motu then that is not the issue), I tried various ports in case the issue came from the power supply circuitry.... I made use my Mac was a lean as possible (so only the key software was running)....
I tried different sampling frequencies, and higher buffer sizes (up to 256) without success...
I tried using Logic Pro but also the standalone version of TONEX, the standalone version of Amplitude etc....
in all cases I kept getting the issue....
And then I decided to remove Motu's driver (which is quite an adventure) and then..... problem solved...
Using the default Mac driver allowed me to get clean audio at all sampling frequencies and all buffer sizes (including 192kHz/32 samples !).... all without trouble and very stable.
The only issue is that removing Motu's driver is unfortunately not the easiest of task..
For some reason they don't supply software to remove it automatically.... So it's a manual task...
I'll outline the steps here...
Please note that if you remove it, you won't be able to use the loopback function... so if this is required I am afraid that unless they supply a new driver that solves this issue, the only option is to purchase a different device (I would suggest Audient ID4 mkII)....
This Motu M2 is actually a good piece of technology with good round trip latency and good audio quality..... It is a shame they do not supply a driver as good as their hardware...
By the way, As of November 2022, I have tried the latest firmware and driver available for Mac...
Anyway, if you try the steps I describe below, let us know the outcome....
How to remove the Motu M2 driver
Read fully before applying any of the steps described.
Open Finder and go to the library directory. Search and any file that has MOTU in its name and delete them. (There will be one in /Library/LaunchDaemons and in other places)
Once done, you will need to remove the driver extension software which is quite involved.
The drive extension files to remove are located in
/Library/SystemExtensions
The directory name will be something like that B4728694-F288-41BD-B7FE-F1445568EAD8
Inside that directory there will be files and one of the file is com.motu.driver.coreuac.dext.dext
In the steps below, the directory to delete is the one with a name like B4728694-F288-41BD-B7FE-F1445568EAD8. Removing it can only be done in recovery mode.
Finding the directly in recovery mode may be tricky... it will be likely like /Volumes/MacOS/Library/SystemExtension… or the closest to that… you know what you are looking for so you’ll find it eventually…. Please read carefully the links below before attempting anything.
If you feel uncomfortable with the steps below you may want to ask some one familiar with this type of operation to actually perform the driver removal.
How to start MacBook running MacOS Ventura in recovery mode is described here
https://eshop.macsales.com/blog/74502-b ... very-mode/
The key is to keep pushing the power-on button until the Mac shows two options for the boot.
How to remove the dext directory mentioned above (driver extension file) is well described here
https://nektony.com/how-to/remove-kext-on-mac
To keep life simple, first disable firevault (if enabled), remove the file as described and then re-enable too.
How to verify the motu driver is effectively removed
1- open the activity monitor and filter data to find any process with the motu name in it.
2- connect the Motu M2 via USB-C and switch it on
3- the only process that should/may be running would be MOTUCoreUACAudioServerPlugin
4- if you see any process with motu in the name (like com.motu.driver.coreuac.dext) and ending in “ext” then the removal was not effective.