Article: Grimm Audio MU1 Music Player Review

[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!
 

[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! 

[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 😀

[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. 

[FredM]

On 10/26/2022 at 8:27 PM, The Computer Audiophile said:

Audio that sounded great through the MU1, but with oversampling turned off via its web interface, was what I'll call piano music.

 

After testing various settings in and outside the MU1, you mentioned that you preferred the non upsampling (0fs) setting in the MU1 with piano music. Calling the transient in the Midnight Sugar track ‘overly sharp’ and even ‘the piano can rip the listener’s ear off’. It got me curious and also puzzled. I’ll try to explain: Although I have preferred the 4fs upsampling since the first day with the MU1 (and actually never touch it since), I tried if I could reproduce your findings. Well, long story short: no. On the contrary actually. I downloaded Midnight Sugar the album (great album btw, thanks!), and must say that I clearly prefer the 4fs setting compared with the 0fs setting (didn’t brother with the 2fs setting). This said, I’m not questioning your findings. But find it interesting what makes that things differ. And thinking more about it, I wonder if the way of testing could have anything to do with it.

 

With upsampling enabled to me it just sound more alive, with more air around the instruments. Also smoother, in a positive way. The strike of a piano key is easier to hear and the tones have a beautiful decay (longer lasting than in a 0fs setting). In more complex pieces, multiple tones just ‘flow’ next to each other and fade out gradually individually. In the specific section (2.25) the piano key is struck hard (and recorded close by?), but the clarity and flow remain. In the 0fs setting it sound (a bit) harsher for me, with less ‘flow’. I would call it an obvious difference (easy to pick in a blind test). Or could the higher Dynamic range (15) of the specific track have something to do with it?

 

With other music I have the same findings, no matter the genre or instruments playing. In my case 4fs is just better, more organic, it opens up, enable the flow. I even listened at some other ‘piano’ tracks to compare. The 4fs benefits remain:

- Nicolas van Poucke, The Schumann collection - Vol 1, Arabeske Op. 18 (modern recording)

- Joan Baez, The very best of, If you were a carpenter (older recording)

- Elbow, Build a rocket boys, Lippy Kids

 

 

On 10/26/2022 at 8:27 PM, The Computer Audiophile said:

The evaluation process I used involved setting Roon's upsampling to 2x or 4x, setting the MU1 to no oversampling, setting the DAC 200 to any number of filters or no filter, then listening, then setting Roon to no upsampling, then the MU1 to 4fs oversample, then listening, then trying a different setting or DAC, etc... The number of combinations is enough to drive anyone crazy. 

 

Once experiencing the 4fs setting, for me there would be no way back to 0fs. All this of course in my setup with my preference, but still our findings quite differ. Hence my confusion. Could it just be a matter of personal preference, or could specific variables result to the different upsampling findings? Perhaps a more general subject is touched (not specific to the MU1). You mentioned that when using additional filter settings,the filters are based on musical content which allows switching between filters depending on the music. Quite a part of the finding cover upsampling/tuning outside the MU1, it would be valuable to understand what relates to what, and ultimately why in your case 0fs is preferred with piano music.

 

With countless tuning combinations possible (filter settings, DSP, convolution setting, upsampling inside the DAC, etc), it’s hard to pin point things. Perhaps double upsampling (in MU1 and T+A DAC 200) can lead to mixed results? Or can early stage digital room correction influence the outcome? When using a specific settings/tuning methods for various types of music, could there be something like a too high level of detail so that it becomes too specific for a review in general? I don’t know. Would it be similar when during a review of for example a Power amp the power cord is swapped for music type A, and even a different pre amp is used for music type B. Besides difficulty in reviewing the product itself with the external variables, as a reader it will also be more challenging to get an understanding of the performance of the product (like I have at the moment 😀 ). Perhaps my hifi tuning knowledge is far below average, but I wonder to what extend an average listener/ reader uses these tuning options in practice (and apply specific tuning for specific music).

 

Looping back to the Grimm MU1, I think it would be interesting if you can try out the Midnight Sugar track with perhaps the tracks above and see how they sound in a minimalist setting (Without the DSP, filters, etc, etc.) Keep it simple. I think that would be closer to (most) users situation, better to understand and more valuable insights. 

 

Please don’t get me wrong, at first I liked your to approach as a welcome addition to existing reviews. But some results seem to differ quite from what others experience (by MU1 users and other reviews). As a suggestion, perhaps it’s an idea to simplify the evaluation approach for gear and perhaps have a separate paragraph for those who have interest and understanding in advanced filter/tuning settings?

 

[FredM]

6 hours ago, The Computer Audiophile said:

The fact that my results are different, is kind of nice to me. I feel very different from most other writers. Not better, just different :~)

 

All feedback and recommendations noted. It's all valuable. Thank you.

Thanks for your responses @The Computer Audiophile 👍 
I guess I’m trying to understand why -per type of music- you seem to prefer different upsampling settings (0fs / 4fs). But fully agree, we just have different findings, all good.
 

Great that you’ve had the opportunity to experience the MU1. When it arrives back at @Analog Audio of Minnesota it can do its magic and create smiles on a lot faces again 😀, nice to occasionally see new MU1 users in the Grimm MU1 topic.