Grimm Audio MU1 and MU2 Music Players

Anyone reading this: Eelco Grimm wil take part in the Dynamic Range Day webcast in approx 1.5 hour. Please enjoy:

On 3/24/2020 at 12:00 AM, FredM said:

The most interesting thing for me is that the FPGA is aimed to match the outgoing digital signal with the ‘default/native’ bit depth/sample rate of the connected DAC. For me this was a new approach

As mentioned in the opening post, I was intrigued by the importance to match the source output format with the ‘native’ format of the DAC chip/module. An recent article from 6Moons goes in more detail, some snippets:

• “But when a DAC runs its own upsampler as the vast majority does but still allows you to defeat it, comparing it to the MU1's own filter can painfully reveal the resolution losses of generic on-chip upsamplers.”
• “ .. helps offload a DAC's heavy calculations when the latter converts music data from the digital into the analog domain.”
• “Throughout the listening period we switched between TotalDAC and T+A DAC 8 and each time found the TotalDAC in non-oversampling mode to be the preferred partner.”

Specifically regarding the Grimm MU1 server/streamer, for me it ticks all the boxes, and more. Perhaps in the Netherlands we’re spoiled, Grimm is well respected and the MU1 is reckoned as a state-of-the-art digital source (the Dutch site hifi.nl has even covered the MU1 in three in depth articles). Some other insights from the latest 6Moons review:

• "In Grimm's Eindhoven shop they spent a lot of time and effort perfecting a switching power supply which became a 2-storied affair. It is prepped for future expansions and was developed using jitter measurements on the audio clock.”
•  “The maximum sample rate for S/PDIF is 192kHz. USB supports 384kHz but eliminates a clock signal. S/PDIF's embedded clock signal meeting the MU1's superior clock is sonically far more relevant than sample rates above 192kHz!”
• “Compared to the Taiko SGM Extreme … the MU1 costs 2.5 times less, weighs 1/10th … and already stands out for its remarkably effortless listening quality.”

The Grimm MU1 in action, on top of a rather exclusive platform 😉

I’ve had the opportunity to listen at the MU1 on three occasions, leaving me (and others) nothing less than astonished with the impact of dynamics and accuracy and yet beautiful stress less sound (sets from €40k to well over €100k). Unfortunately it’s not my expertise to (even try) to describe a sound, I’ll just keep admiring those who can 😊.

For me the MU1 has all the advantages of an one box solution (synergy, in-house end to end design), without the disadvantage: upgrade flexibility. As I have no relevant electronic or software DIY skills myself, Grimm has a good track record supporting its customers with future upgrades for their products. This is very comforting in a digital area where new discoveries and improvements are a constant.

Oh dear.. I almost forgot, as @Nenon, @RickyV and @beautiful music have already requested, here's a link 😘

https://6moons.com/audioreview_articles/grimm/

Here you go, please let me share my journey/ process to decide for the MU1. In a follow up post I’ll attempt to describe the music experience with the MU1. Besides getting more familiarised with the MU1 at first, hopefully my enthusiasm is settled down (and my night sleep is also back to normal by then). Hopefully I’ve also thought of one simple word to describe the MU1, it isn’t only the qualities, there is more, hard to grab. 

As some of you might know, my quest for a decent digital front end started a while ago, to be combined with Harbeth speakers, Primaluna Dialogue amp, Metrum DAC in a medium sized room with some acoustic treatments. A joyful system, and very much to my liking. As part of my interest/this hobby I tracked the latest and rapidly changing front end developments. With Linn’s mantra ‘source first’ in my head, I decided the source should be the cherry on top.

As several source (related) products where launched: server, endpoint, OS, clock, switch, psu’s and cabling, eventually I preferred an one-box-solution. Having no technical knowledge or relevant DIY skills to build something myself, I reckon it would be difficult and time consuming to determine a good mix of devices/cabling/.. Most would become trail and error in my case. With already some devices in and on the hifi cabinet, I also wanted to avoid a plethora of source related devices/cables.

There where not that many servers on the market to my liking. When the hifi tailored AudioLinux software got more traction. I was eying a particular server with this kind of software onboard. Long story short: this appeared to be a dead end street, with a year waisted. Meanwhile -on the opposite side of the system- the idea of an active speaker system was growing on me. Similar to a one box source, an active speaker system is designed and tuned as one. The Grimm LS1, Dutch & Dutch 8c’s and Kii Three would be the usual suspects.

When hearing the D&D and Kii Three for the first time I was surprised with their performance. Later I listened at the Grimm LS1 at a Dutch audio show (XFI 2019), their statement LS1be speaker system was connected with the MU1. What an experience, like a goosebumps inductor, once 3 times during one song..! This really grabbed me. Of course I haven’t listened at all speakers in the world, although more than enough to know this was very special. A fair amount of the afternoon I just sat in the room enjoying song after song. I remember driving back home, ‘I’ve just found a gem’.

A while later at a dealer I had a direct comparison with the D&D 8c and two LS1 models from Grimm. The D&D and Grimm are both stunning speakers. I favoured the Grimm LS1a, where the LS1be with the dmf subwoofers in my experience where just magical. I was in love. Unexpectedly I was able to go ‘all in’ and sold my complete system and bought the LS1be’s. As much I liked my previous system, I never looked back. The LS1’s simply play in another league.

Regarding the source I still was at square one. Oddly the MU1 wasn’t on my radar at first. In fast forward I went thru a similar thought process as before, pondering about separates vs an one-box-solution. I even thought of building my own server. I did some research on fanless cases, motherboards, RAM, cabling, psu, internal cards/bridge, etc. Where I have utmost respect for those who are skilled and have the time to discover and create servers themselves and share their insights online (which I enjoy reading, many thanks @seeteeyou, @austinpop, @bobfa, @romaz, @Nenon and many more!), I reckoned a turnkey solution would be more appropriate for me. 

As the MU1 was well received in the Dutch hifi press I realised the answer could be right under my nose, with the additional advantage that speaker and source will match excellent. Then, the more I read about the MU1, the more fascinated I got, hence this topic. Not looking on Grimm MU1’s sound quality, there are some other aspects which I find appealing and are perhaps worth mentioning:

• The design approach, as first mentioned in the OP the importance of matching the format of the source with the ‘native’ format of the DAC. Also walk the talk by choosing for S/PDIF via AES/EBU as the single digital output which carries the clock (quite daring as USB is most commonly used for consumer products).
• Custom end-2-end design and build, only the NUC and (optional) SSD are of the shelve components. i.e. the psu of the MU1 is developed by jitter measuring at the clock. Track record developing oscillators (Guido Tent, Tentlabs), like a server build by jitter experts.
• Deep understanding how ‘music works’, with Eelco Grimm being a front runner for Loudness Normalisation (ie analysing more then 4 million albums on Loudness, which recommendations are implemented by Tidal)
• As with other Grimm products, the MU1 isn’t just buying a server/streamer. Upgrade possibilities will appear, making the MU1 a future proof investment. Sure it’s a lot of money, but with good value imho. The MU2 is already announced (MU1 with internal DAC). Grimm is also working on custom playback software, as a free alternative for Roon which will deliver a higher sound quality.
• It took the Grimm team of experts (with Eelco and Guido also being university lecturers) about 4-5 years to develop the MU1. No way I will be able to match that with source (related) devices, where I mix and match products myself.

So far my personal ‘journey post’, I hope it was interesting and perhaps useful for some. As I’ve enjoyed reading about the process and discoveries of others online, nice to share something in return. 

Oh, @beautiful music, here’s a nice picture, as requested 😋

Can't edit the opening post, here's another MU1 interview. Eelco Grimm and Guido Tent give some details on developing the MU1 (some go over my head), followed with a review by Jason Kennedy from The Ear.

Update: now that the MU1 is settled in, it’s time to share my listening journey with the Grimm Audio MU1. As mentioned earlier, please don’t expect a professional like write up where several hifi components are compared and carefully described with a rich hifi/ audiophile vocabulary. Even after about two months of listening I couldn’t catch the MU1 in an one word summary. There is more to it, which I’ll explain later. 

To share my personal thoughts with you, this ‘listening journey’ update has three perspectives. Please let me start with the first, and most important:

Objective listening experience 

Here’s a chart on how the MU1 objectively sounds:

This is probably the most fact based experience I can share with you*. The items on the bottom represent the listening sessions, the value per bar displays the number of goosebumps per session. I’ve never experienced this before, it’s great to have such an (emotional) connection with the music. With the MU1 I’m not listening technical and dissect a song, it’s about the joy of listening, where my foot starts tapping, etc. (*Disclaimer: I’m not a person with a notebook and pencil at hand during listening sessions, I would say it touches five on an average evening).

So perhaps the MU1 can best be described as a goosebump inductor, or as a pleasurability generator: “Canadian researchers have suggested that when humans are moved by music their brains behave as if reacting to delicious food, psychoactive drug, or money. The pleasure experience is driven by the chemical dopamine, which produces physical effects known as "chills" that cause changes in heart rate, breathing, temperature and the skin's electrical conductance. The responses correlate with the degree to which people rate the "pleasurability" of music. Dopamine release is greatest when listeners had a strong emotional response to music. "If music-induced emotional states can lead to dopamine release, as our findings indicate, it may begin to explain why musical experiences are so valued,” wrote the scientists.”

Listening impressions 

What impresses most during the first weeks is the lack of listening fatigue. Three, four, five hours without a problem, no limit. Great to listen song after song, album after album. Or just sit back and let Roon serve its picks and discover new tunes. This effortless comes with a warning, it’s addictive. Thanks to separated listening room (with no mrs M. around) listening till 2.00-3.00 AM is no exception, like having a candy shop at home.

New for me, the volume also doesn’t seem to trigger listening fatigue. Delicately soft or screaming loud with striking dynamics: it’s all good, where the volume slider in Roon is very convenient to simply adjust things on the fly (with peace in mind, thanks to a ‘comfort limit’ setting). When listening at low levels, there is still a sharp picture, details and image remain. I mostly listen at folk/vocal, jazz, electronic and pop/rock btw.

What could be a down side for some: great recordings sound great, exceptional recordings sound exceptional and lesser quality recordings show there shortcomings. I have the impression that the MU1 doesn’t overemphasis. Replay is transparent and honest, it’s fast with lots of details (with for example the beautiful gradually dying of a piano tone or the tip of a drumstick hitting a cymbal) but not in an overemphasised / in your face way.

Most difficult to describe is the ‘flow’ of the music, I don’t know if this is related with the LS1be also in play. I’ll try to explain what I mean with ‘flow’ in an other context: It like riding a rocking horse on a carousel. When sitting on a rocking horse (normal listening) is very entertaining, the extra joy (flow) is created by the carousel, where al individual pieces (instruments) seem to move in same direction, and each have their own character next to you: moving up and down, sideways and with their own pace on the carousel platform: All instruments towards the same direction, being surrounded and sucked into the music. I hope this makes any sense, please excuse me, I couldn’t think of an easier way to describe it. At least you now know the limitations of my writing skills 🙂

Relaxed listening 

Also worth mentioning is the impact on the hobby. After adding the MU1 in the set, it seems everything falls into place. I still occasionally read about hifi news and developments, but in a more distanced way. 

Despite knowing there are some (potential) upgrade possibilities, the ‘upgrade bug’ has left the building. With power cables, network input and perhaps vibration as the usual upgrade suspects, I don’t feel a desire to improve in a specific area (I’m currently using a white Walmart power strip, go figure). The chain seems very well balanced. Endgame? Yes. 

Who knows what the future brings. If I would change things, I reckon it’ll most likely be driven out of curiosity (not from a desire to improve or fix certain area’s). It’s also a comforting thought that Grimm has a reputation for offering upgrades on existing products, so why pursue upgrades: Better to relax and enjoy the music. A big thumbs up for the Grimm team, a stellar performance!