In addition to the addition of UPnP and Tidal Connect support, firmware v2.0.0 makes the Grimm MU1 and MU2 certified Roon Ready Endpoints.
As an MU1 owner (see review), I’m very happy to see the Roon Ready certification with this firmware update as this brings with it some Roon-related niceties including the use of Roon’s volume control to control the MU1 or MU2’s volume as well as the ability to view the complete signal path in Roon with a click.
Of course people who’ve been waiting for a non-Roon playback solution have more to cheer for as the addition of UPnP brings with it the option to use any UPnP app including JPlay to control your Grimm device (note: you need to run a separate UPnP server as the MU1 and MU2 do not support this functionality). And I view Tidal Connect as a great way to stream without the additional cost, albeit without the all-important functionality, of Roon.
Firmware v2.0.0 was 18 months in the making and it also includes a few additional fancy functions. Here’s one as described by Grimm:
The second novelty is a bit test function. By playing a dedicated Grimm Audio test album with different sample rates and bit depths per track you can test whether your digital audio pathway conveys all bits unaltered. Now you can test Roon and your UPnP playback easily yourself.
Novelty is fun!
Here’s the press release:
Big Firmware Update for MU1 and MU2
November 4, 2025
We are very happy to let you know that we just released a big firmware update of our MU1 and MU2 streamers. For the first time it becomes possible to use the MU1 and MU2 with other network streaming sources than Roon since we added support for UPnP and Tidal Connect. Via UPnP popular music apps such as JPlay and BubbleUPnP can now be used with the MU1 and MU2. Please note that a UPnP server should be running in the network, the MU1 and MU2 do not offer that function.
Equally important is the addition of a Roon Ready Endpoint. We still see Roon as the most convenient and powerful music player and offer our full support to that platform. Now that the MU1 and MU2 became a certified Roon Ready Endpoint, they have their own identity in the Roon app, with a MU icon and a volume control with decibel scale. You can even check the full internal signal path of the MU1 and MU2 by clicking the blue button in the Roon interface. Important for customers with very large music catalogs is that the MU1 and MU2 now integrate perfectly with an external Roon Server.
There are two new features that deserve a blog post of their own so we will only briefly introduce them to you. First of all we added Loudness Normalization via UPnP and Tidal Connect. When using this function albums are played at equal loudness so you do not need to adjust the volume anymore when changing to tracks of another album – even if it is from a completely different genre. The implementation in the MU1 and MU2 has no impact on the sound quality at all since it is just an automatic offset to the high quality built-in volume control. The second novelty is a bit test function. By playing a dedicated Grimm Audio test album with different sample rates and bit depths per track you can test whether your digital audio pathway conveys all bits unaltered. Now you can test Roon and your UPnP playback easily yourself. More about these two unique features later.
Under the hood many more things have changed. The system runs a new Linux OS version, we addressed a couple of rare bugs, etc. Our team has been working on this update for 18 months, so you can imagine the effort that went into it. To reflect the weight of these updates, the MU1 firmware is called “v2.0.0” and the MU2’s “v1.0.0”. This is our engineer’s original vision of how the MU1 and MU2 firmware should feel and function. A true milestone.
To learn more about the updates, please check out the updated MU1 and MU2 software manuals, the Quick Start manuals and the change logs. These can be found on the downloads tab of the product pages of the MU1 and MU2.