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Grimm Audio MU1
The MU1 is the ultimate digital music source. Combined with the LS1, it forms a peerlessly elegant High-End audio system.
We wanted to develop the most accurate audio source we could imagine. In our experience, the human hearing system shows an incredible sensitivity to anomalies. Even unimaginably small aberrations appear to be audible. In principle, digital audio does offer perfect reproduction. Its sonic quality, however, is limited by the implementation accuracy of the physical and mathematical laws that affect the conversion from one format to another. Grimm Audio strives to bring you confidence that all technical details are taken care of to the greatest extent so that the reproduction system steps out of the way of the music.
With the MU1, our goal was to set a new benchmark in music player design. The Linux-based computer system brings solid data integrity. Our in-house-designed FPGA interface board, which forms the heart of the MU1, offers breakthrough performance levels in format conversion and receives automatic updates whenever we have pushed the boundaries again. Needless to say, the MU1 features our trademark ultra-low jitter clock. This is a music player worthy of the name Grimm Audio.
Once excellent sound quality is ensured, the quality of a music player is then defined by the user experience. For this, we partnered with Roon Labs, who in our opinion are in the lead when it comes to a rich and engaging music experience that appeals to your whole family. The MU1 runs the Roon Server, so no extra installs are necessary. Just pick up your tablet and experience the music. For customers who prefer to only run a simple playback system without Roon’s extras, we offer a UPnP renderer function and Tidal Connect.
The MU1 combines seamlessly with the LS1 playback system. Of course, the virtues of the MU1 can also be realized with DACs from other manufacturers. Because we love to create a stunning look for our equipment, the boundlessly versatile system is housed in a cabinet of minimalistic elegance, so the MU1 will easily become the gem of your living room.
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Professional Reviews 92/100
Deliciously Crispy
Sound Quality
95/100
Build Quality
89/100
Features Usability
91/100
Value for Money
86/100
Built around FPGA resampling and ultra-low-jitter clocking, the MU1 transforms a capable DAC into a more revealing, spatially convincing digital front end. HiFi News heard exceptional mix insight and three-dimensional focus, while SoundStage Solo praised its fluid, vivid musicality without glare. Its processed AES/EBU output is the headline act, delivering weight, resolution and natural flow.
What Reviewers Are Saying
Pros
Processed AES/EBU output delivers substantially greater transparency, body, low-level detail and musical coherence than USB.
Creates a deep, focused, three-dimensional soundstage with strong separation and convincing image density.
Combines Roon Core operation, optional internal storage and digital-input processing in an unusually versatile hub.
&
Cons
Its premium price places it firmly in cost-no-object territory.
The signature FPGA processing advantage is tied to AES/EBU or S/PDIF; USB output does not receive the same treatment.
SOUND QUALITY PERFORMANCE 95/100
Reviewers repeatedly describe an unusually transparent, fluid and musically involving digital source, especially through its processed AES/EBU outputs. The preferred configuration is important: AES/EBU with Grimm's processing is consistently reported as markedly stronger than direct USB/network paths, while one reviewer found 4FS oversampling too sharp in a particular DAC system.
Overall Sound
95/100
Across reviews, the MU1 is praised for exceptional resolution, tonal richness, natural flow, dense imaging and a notably fatigue-free presentation. SoundStage Australia called it vibrant, balanced, dynamic and emotionally involving, while Hi-Fi News and The Ear found it among the most musical and exciting digital sources they had heard. Results are setup-sensitive: reviewers most strongly favor the AES/EBU output and preferred oversampling settings varied with the partnering DAC.
Digital Signal Integrity
96/100
The custom FPGA processing, extremely low-jitter clocking and reclocked AES output are central to the MU1's acclaim. Multiple reviewers heard greater clarity, body, separation and low-level detail through AES/EBU, with Audiokey Reviews and Part Time Audiophile reporting a substantial step beyond USB output. Hi-Fi News likewise found the resampled and reclocked AES3 feed clearly superior to the direct USB-derived output.
FEATURES USABILITY PERFORMANCE 91/100
The MU1 combines Roon Core functionality, network playback, storage options, digital-input reclocking and extensive digital hub duties in a notably coherent package. Its strongest operation is tied to Grimm's AES processing path, so users planning around USB output should note that it does not receive the same proprietary resampling and reclocking treatment.
Streaming Software
91/100
Roon integration is widely regarded as a major strength, and Part Time Audiophile called setup among the easiest music-server experiences it had encountered: connect it, let it detect Roon, and play. The MU1 supports Roon Server and endpoint operation, Tidal, Qobuz, UPnP and web-based configuration, while the included remote and physical controller add useful local control.
Features Connectivity
92/100
The MU1 is unusually flexible as a digital hub, offering dual AES/EBU outputs, S/PDIF and optical inputs, LS1 connectivity, Ethernet, USB storage support, optional internal SSD storage and multichannel capability. It can process external digital sources as well as streamed and stored music, but USB output is not the route for Grimm's full FPGA processing and there is no conventional USB audio output in the reviewed implementation.
Assessments of Build Quality, Usability, and Overall Propositions.
Build Quality
89/100
Reviewers describe the MU1 as elegantly designed, well finished and thoughtfully engineered rather than merely luxurious in outward heft. The fanless low-noise implementation, shielded clock section and carefully executed switching supply receive specific praise, although long-term durability commentary is limited.
Value for Money
86/100
At roughly €9,800 to €14,800 depending on market and storage configuration, the MU1 is clearly a costly music server and transport. Part Time Audiophile and The Ear both identify the price as its principal drawback, but The Ear considered the asking price warranted by its performance, while SoundStage Australia's reviewer bought the review sample and offered a strong recommendation.
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Authorized dealers for Grimm Audio MU1
- The Audio Association — in-store — Anaheim, California, United States (website)
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- Atelier 13 Audio — in-store — Forest Hills, Tennessee, United States (website)
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- Audio Excellence (CH) — Switzerland (website)
- Audio Gallery — online and in-store — Las Rozas de Madrid, Comunidad de Madrid, Spain (website)
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- Audio Vision San Francisco — online and in-store — San Francisco, California, United States (website)
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