Article: Grimm Audio MU1 Music Player Review

[The Computer Audiophile]

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[FredM]

“ The Grimm Audio MU1 digital music source is absolutely the right product for many listeners in our wonderful hobby. If perusing the MU1 thread here on Audiophile Style is any indication, most people set it and forget it, at either 2fs or 4fs oversampling. The concept and validity of an external up/oversampling device has long been proven highly effective in many audio systems. The MU1 takes this a step further by including a Roon core and an advanced FPGA working to extend the capabilities of Roon, to deliver a pristine audio signal out to a DAC. “
 

Imho spot on 👍. It’s an one box solution that offers turn key musical enjoyment. End game for many. Personally one of my best ever hifi choices, it just keeps amazing me.
 

Thanks for sharing your experience Chris, a well written review with nice new insights which were untouched in the other MU1 reviews. I can imagine that (heavy) thinkering/tweaking curiosity (experimenting with oversampling, DAC filters or DSP and Convolution settings, I didn't knew what it is 😀) require some determination given the bunch of combinations. Thanks!
 

[The Computer Audiophile]

5 minutes ago, FredM said:

“ The Grimm Audio MU1 digital music source is absolutely the right product for many listeners in our wonderful hobby. If perusing the MU1 thread here on Audiophile Style is any indication, most people set it and forget it, at either 2fs or 4fs oversampling. The concept and validity of an external up/oversampling device has long been proven highly effective in many audio systems. The MU1 takes this a step further by including a Roon core and an advanced FPGA working to extend the capabilities of Roon, to deliver a pristine audio signal out to a DAC. “
 

Imho spot on 👍. It’s an one box solution that offers turn key musical enjoyment. End game for many. Personally one of my best ever hifi choices, it just keeps amazing me.
 

Thanks for sharing your experience Chris, a well written review with nice new insights which were untouched in the other MU1 reviews. I can imagine that (heavy) thinkering/tweaking curiosity (experimenting with oversampling, DAC filters or DSP and Convolution settings, I didn't knew what it is 😀) require some determination given the bunch of combinations. Thanks!
 

Thanks so much @FredM. I'm very grateful your MU1 thread in the forum has provide so much information. Seeing how everyone uses the MU1 and the success they've had is really nice. 

 

Question: Do you use internal storage?

[FredM]

1 hour ago, The Computer Audiophile said:

Thanks so much @FredM. I'm very grateful your MU1 thread in the forum has provide so much information. Seeing how everyone uses the MU1 and the success they've had is really nice. 

 

Question: Do you use internal storage?

You’re welcome, and also thanks to the other Grimm MU1 users who also share their MU1 experiences. Together we’re able to help fellow MU1 users, and others who are interested of course. It never hurts to help 🙂

Yes, I use a 2TB SSD, that’s sufficient for my needs. Next to my local albums I just love how Roon Radio suggests tracks/albums, great to discover and enjoy new music! 

[bobfa]

Does it only run Roon or are there other choices such as Squeezebox?

 

 

[PYP]

26 minutes ago, bobfa said:

Does it only run Roon or are there other choices such as Squeezebox?

 

 

From one of the US Grimm dealers:  "It currently supports only Roon. However, there is an update coming out in 2022 that allows it to be used with other controller software. I assume that means they will be adding UpnP/DLNA support. "

[znorter_1]

..waiting for MU2 (the "real" one box-only)*
*DAC inside 😉

P.S. 

15 hours ago, FredM said:

Convolution settings, I didn't knew what it is

me, too.
Is it a simple option to activate on ROON DSP settings?

[stefano_mbp]

28 minutes ago, znorter_1 said:

Is it a simple option to activate on ROON DSP settings?

 

[znorter_1]

36 minutes ago, stefano_mbp said:

 

OK. "Just" for Win and MacOS.

[stefano_mbp]

2 minutes ago, znorter_1 said:

OK. "Just" for Win and MacOS.

… on Linux too … using HQPlayer or JRiver

[Richh84]

Any update from grimm on why the roon convolution w/ grimm upsampling issue?

[znorter_1]

1 hour ago, stefano_mbp said:

… on Linux too … using HQPlayer or JRiver

..a must have PC/Laptop (in the hifi chain) is necessary.
Wait: is it possible to use an APP? I don't know if JRiver and/or HQPlayer are on android/iOS APP version.
It would be wonderful... to bypass ROON 😛 ... I mean, to check the "SoundQuality", not talking about the "Music management", a ROON to die for!
 

[The Computer Audiophile]

1 hour ago, Richh84 said:

Any update from grimm on why the roon convolution w/ grimm upsampling issue?

I can only speak for myself on this one. With so many variables, it's probably best to know about my issue using convolution with the MU1's oversampling, but not think much more about it. All convolution filters are different, convolution engines are different, DACs are different, etc... My issue could be a non-issue for everyone else. I really wish others with the MU1 used convolution and could give me some feedback on how it sounds in their system with oversampling set to No/2fs/4fs. 

[Richh84]

I might be testing this waiting on demo unit

[FredM]

5 hours ago, znorter_1 said:

..waiting for MU2 (the "real" one box-only)*
*DAC inside 😉

P.S. 

me, too.
Is it a simple option to activate on ROON DSP settings?

The first question imho could be, do you need to discover and want to worry about convolution engines, DSP settings etc?
 

I’ll try to put this consideration in context: The MU1 review above is unique in its kind, as it really focuses on several possible variables to tune the sound (experimenting with Roon, MU1 and DAC settings and even perhaps other devices/software, I don’t know, it’s beyond my knowledge). This all in the specific context of Chris’ system topology. I think it’s very nice to see this specific focus in the review, as an interesting and good addition to the other already existing reviews (you can find several reviews on the Grimm website).

 

As Chris also mentioned in the review -and I think this is worth emphasising- that for 99% of the listener needs the MU1 as-is just works perfect. Besides the sound quality, the MU1 is unique in its kind to offer several functions in a single box, tuned as one (core, psu, clock, upscaler, ..). So no more mixing and matching with hifi devices/cables/psu’s. Simplicity and elegance are high on the agenda at Grimm HQ. Turn key high end. On the opposite side of the spectrum it is course possible to explore several tuning possibilities, but is not needed in 99% of the situations. Just plug, play & enjoy 👍. Personally I find it very relaxing to trust the Grimm team, they’re able -far far better than myself- to introduce improvements. The MU1 is a flexible platform, with new improvements released and announced.
 

And as you already mentioned, with the upcoming MU2 (incl DAC) a further simplicity level is likely ahead 😀

[znorter_1]

2 hours ago, FredM said:

And as you already mentioned, with the upcoming MU2 (incl DAC) a further simplicity level is likely ahead 😀

Oh, yeah.
 

[57gold]

So exactly what does this $10.5K box do that say a $2.5K Mac Studio with 2TB of SSD and Roon software can't do?

 

Alternatively, I'm guessing that with say HQ Player on the Mac Studio, it can do things that the Grimm unit cannot.

 

Looks nicely made.

[The Computer Audiophile]

1 hour ago, 57gold said:

So exactly what does this $10.5K box do that say a $2.5K Mac Studio with 2TB of SSD and Roon software can't do?

 

Alternatively, I'm guessing that with say HQ Player on the Mac Studio, it can do things that the Grimm unit cannot.

 

Looks nicely made.

Like everything, it isn’t for everyone. The built-in DSP is “idiot” proof, with a couple radio buttons to click. There is nothing to update when a new OS comes out or OS settings to adjust etc… plus, the Grimm DSP is proprietary, and something not available elsewhere. 
 

That said, if you have a Mac and HQP, and a DAC that accepts the stream coming from that, you can do incredible things. The learning curve can be steep though. 
 

I’m glad we have options. 

[pmorali]

2 hours ago, 57gold said:

So exactly what does this $10.5K box do that say a $2.5K Mac Studio with 2TB of SSD and Roon software can't do?

 

Alternatively, I'm guessing that with say HQ Player on the Mac Studio, it can do things that the Grimm unit cannot.

 

Looks nicely made.

 

57gold, I'll try to give you my perspective on your question.  For context, before the MU1, I too was running my Roon core on a Mac, albeit a Mac mini, with a 1TB SSD, which I ran via ethernet into a Lumin U1 streamer (as a Roon endpoint), then into my DAC.  

 

So I am just providing my perspective (in my room, on my system, to my ears...) since I experienced and compared both setups; I do think the Mac mini or Studio as a Roon core is a good solution.

 

I can't tell from your post if you are running your Mac into your DAC (via ethernet or USB), or if you have a streamer in between, so I'll assume for purpose of this answer that you run it directly into your DAC (which may be incorrect). 

 

To address this first, the MU1 is a Roon core, same as your Mac Studio, so you can run HQ Player on the MU1 as you do on your Mac Studio today. The Roon core on the MU1 is the same as on the Mac (v2.0), except running on a different OS, which is invisible to the end-user.

 

To answer your specific question, relative to a Mac Studio Roon core, the MU1 integrates a Roon core and a re-clocker, with the following four primary benefits (there may be more but I chose to focus on what I personally consider the primary compounding benefits):

 

1.  The MU1 is architected with two CPUs, an Intel i3 NUC dedicated to running the Roon core, and an FPGA processor board dedicated to running Grimm Audio (optional) DSP functions (up/down-sampling, digital volume control). This is to minimize the noise resulting from loading a single CPU architecture with "dirty" DSP software, and also improve SQ through higher-quality DSPs;

 

2. A high-performance low-jitter clock to convert and re-clock the asynchronous ethernet or USB data signal into a high-quality synchronous data signal served to the DAC via S/PDIF or AES/EBU. This is to minimize jitter;

 

3. A high-performance DSP to up/down-sample PCM or DSD into what Grimm Audio deems ideal for most DAC, thereby enabling the DAC to focus on its primary D to A function, without te noisy "distraction" from having to re-clock and re-sample the data stream first;

 

4. A low-noise power supply to power the MU1 aimed at minimizing noise.

 

So comparing your $2.5K 2TB SSD Mac Studio Roon core to the $10.5K MU1 is indeed a steep jump, which rightfully begs your question.  My 1TB Mac min Roon core/Lumin U1 combo was "closer", at ~$8.5K.

 

I run a 100% digital path, and I felt that the Mac mini/Lumin combo was becoming a weaker link which I needed to explore and address (particularly the server portion of the combo). I am not an engineer as you can tell.  But I did my research which pointed me to the MU1.  I pulled the trigger and I have found that the resulting SQ is extraordinary, from increased flow, dynamic range, instrument/voice 3D separation and positioning, and coherence.  I had never derived so much emotion from my music library, which now often draws tears to my eyes... 

 

My 2 cents, for what it is worth.

[George Hincapie]

Fred,

If one is not interested in upsampling at all and instead prefers to play digital files 'as is'  does the MU1 offer SQ improvements for that use case in comparison to competing solutions?

[57gold]

Thanks pmorali for sharing your experience with this product.

 

Still not sure I understand its functions / capabilities.  The company's website seems to indicate that it is a DAC (Do you use it as a DAC? Review has it hooked up to super DACs.), has limited built in upsampling capabilities, there is no info on its capabilities with respect to player software like HQPlayer and dealing with upconverting to DSD 128 or higher using its powerful filters.  

[FredM]

6 hours ago, George Hincapie said:

Fred,

If one is not interested in upsampling at all and instead prefers to play digital files 'as is'  does the MU1 offer SQ improvements for that use case in comparison to competing solutions?

Hi George, 

 

With the Grimm MU1 usampling can be set at 0, 2 or 4fs, if you would like to disable upsampling, you can. Then, to quote Chris:

“disabling oversampling still enables the listener to take advantage of the MU1's stellar clocking circuit and clean digital audio output to the DAC. What I heard with all music, once I settled on my preferred filter setting, was terrific through the MU1”

(upsampling is maxed out at 4fs with a purpose, this enables to also transfer the clock signal from the MU1 to an external DAC via AES)

Switching between upsampling settings on the MU1 can be done on the fly, in the webinterface (1 click) or via the menu on the device. As said, 99% of the users appear to prefer upsampling with the MU1, just set it once (for playback of all genres, albums, tracks, etc). 
 

I’m afraid I can’t answer how the MU1 in a non-upsample setting would compare with other products, it’s a quite specific test case. The closest I’ve seen are Chris’ findings above, with different upsampling preferences per music (still both with the MU1 as player). Comparing the MU1 in a non-upsampling setting with another product or products even would introduce another variable to the test😬. I think a dealer can help best. I would just simply start with the MU1 out of the box and see if further actions are needed. 

[The Computer Audiophile]

5 hours ago, 57gold said:

Thanks pmorali for sharing your experience with this product.

 

Still not sure I understand its functions / capabilities.  The company's website seems to indicate that it is a DAC (Do you use it as a DAC? Review has it hooked up to super DACs.), has limited built in upsampling capabilities, there is no info on its capabilities with respect to player software like HQPlayer and dealing with upconverting to DSD 128 or higher using its powerful filters.  

No DAC in MU1. Word on the street is the MU2 will contain a DAC. 

[skatbelt]

9 hours ago, George Hincapie said:

Fred,

If one is not interested in upsampling at all and instead prefers to play digital files 'as is'  does the MU1 offer SQ improvements for that use case in comparison to competing solutions?

 

I think the MU1 (and other dedicated music servers) is best understood from a technical perspective. Computers in general are noisy. In the MU1, an attempt has been made to keep this to a minimum by means of a combination of (bare bone) hardware and proprietary software. Much attention has been paid to the power supply, isolating the incoming Ethernet signal and bypassing USB as a connection to the DAC. Add to that state of the art clocking (the area Grimm is famous for) and you reach a completely different level than can be achieved with a standard computer like a Mac.

 

The upsampling is just a bonus. But is does something special in my eyes, something I've never heard from any HQPlayer configuration. It is more similar to Chord M-Scaler territory. HQPlayer is a very good 'bang for the buck' though.

[George Hincapie]

14 hours ago, FredM said:

Hi George, 

 

With the Grimm MU1 usampling can be set at 0, 2 or 4fs, if you would like to disable upsampling, you can. Then, to quote Chris:

“disabling oversampling still enables the listener to take advantage of the MU1's stellar clocking circuit and clean digital audio output to the DAC. What I heard with all music, once I settled on my preferred filter setting, was terrific through the MU1”

(upsampling is maxed out at 4fs with a purpose, this enables to also transfer the clock signal from the MU1 to an external DAC via AES)

Switching between upsampling settings on the MU1 can be done on the fly, in the webinterface (1 click) or via the menu on the device. As said, 99% of the users appear to prefer upsampling with the MU1, just set it once (for playback of all genres, albums, tracks, etc). 
 

I’m afraid I can’t answer how the MU1 in a non-upsample setting would compare with other products, it’s a quite specific test case. The closest I’ve seen are Chris’ findings above, with different upsampling preferences per music (still both with the MU1 as player). Comparing the MU1 in a non-upsampling setting with another product or products even would introduce another variable to the test😬. I think a dealer can help best. I would just simply start with the MU1 out of the box and see if further actions are needed. 

 

Thank you my friend, I appreciate the response.