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Grimm Audio MU2
We are convinced that smart integration of functions yields higher audio quality. The MU2 combines a music streamer with a superb DAC and a reference quality analog pre amp. Its built-in DAC takes full advantage of the Grimm Audio low jitter clock and high performance FPGA processor. A relay based analog volume control enables the MU2 to become the true ‘hub’ of your hifi system for both digital and analog sources. Just like with its sister product, the ‘digital output’ MU1, a Roon Labs server is on board so no external computer is needed to enjoy perfect streaming.
At the heart of the MU2, Grimm Audio’s proprietary Major DAC can be found. It is of a groundbreaking discrete design that makes optimal use of our own FPGA board. In a unique way our high resolution Pure Nyquist upsampling filters are combined with a fundamentally flawless 11th order noise shaper of 1.5 bit. If you like to read more about this technology, please check out the Major DAC blog
As a result the MU2 reproduces micro-details so well that it allows a deep emotional connection to the musical performance. The stereo image is of groundbreaking quality. Its serenity invites prolonged listening sessions.
If you love your loudspeakers and power amplifiers but long for a fundamental update in sound quality and streamer experience, the MU2 is designed for you.
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Grimm Audio MU2 — Summary
Grimm Audio's MU2 is a one-box streaming DAC/preamp that pairs startling transparency with warm musical engagement. Its sonic signature combines ultra-low clock jitter, an FPGA-driven Major DAC and relay-based analog volume to deliver blistering transients, tight weighty bass, fleshed midrange vocals and crisply detailed treble inside an expansive, three-dimensional soundstage. As noted by K. E. Heartsong and Andrew Everard, the MU2 reveals microdetail without losing musical flow. The compact, minimalist chassis offers web and IR control, optional internal SSD and integrated Roon Core, making it a versatile hub for systems from active speakers to separates. For listeners seeking a reference-grade streaming front end that simplifies a system without compromise, the MU2 is a highly capable, thoroughly engineered choice.
Pros
- Exceptionally transparent, highly resolving presentation that uncovers microdetail and produces a wide, three-dimensional soundstage.
- Feature-rich, true one-box design — integrated Roon Core, FPGA-based Major DAC, relay-based analog volume control and optional internal SSD — serving as streamer, DAC and preamp.
- Outstanding dynamics and bass control with natural, fleshed midrange and engaging treble that preserve musical momentum.
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Cons
- Steeper-than-usual learning curve and setup quirks (top-wheel operation, Roon integration) that may require time or reading the manuals.
- Premium price and a few reviewers questioned whether some internal component choices fully justify the cost for every buyer.
Transparency
93/100
Multiple reviewers emphasise extreme resolution and lack of veil: AudioKeyReviews describes the MU2 as effectively removing a barrier between listener and master-tape, and HiFi News calls it an "exceptional player". Technical design details (exceptionally low-jitter clock, relay-based analog volume, fully symmetrical analogue output) and reports of 'neutral' and 'just music' presentation (Alpha Audio) support a very high transparency score, though canonical phrases like 'black background' are not used explicitly in the reviews.
Sound Quality
92/100
Dynamics
92/100
Dynamics and transient response receive strong praise: AudioKeyReviews calls its transients 'blisteringly fast', HiFi News highlights drive, weight and sharp focus, and reviewers note excellent micro- and macro-dynamic layering. The unit preserves attack and rhythmic propulsion very well, supporting lively, engaging playback.
Soundstage Imaging
92/100
Several reviews report expansive, well-defined soundstages: AudioKeyReviews describes a volumetric, fully dimensional soundstage; HiFi News notes 'finely etched and free-breathing' images with musicians placed convincingly in space. Imaging precision and depth are clear strengths of the MU2.
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Build Quality
90/100
Grimm's engineering choices (relay-based analog volume, in-house SMPS with series/shunt regulators, measured low-jitter clocks, FPGA Major DAC) point to careful construction and thoughtful circuit design praised by multiple reviewers. Alpha Audio notes some reservations about cost-versus-component choices (no linear PSU, compact chassis), which tempers a perfect score.
Features Connectivity
94/100
Very feature-rich: integrated Roon Server/Core, streamer (Ethernet), FPGA Major DAC, AES/coaxial/optical inputs, analog XLR and RCA in/outs, headphone output, remote and web control, optional internal SSD and USB/NAS support, and relay-based analog volume. This combination places it in the fully-featured band for a modern high-end streaming preamp.
Value for Money
89/100
Value assessments are broadly positive but mixed: AudioKeyReviews and Audiophilepure argue the MU2 offers exceptional performance for its price (even outperforming more expensive in-house combos), while Alpha Audio questions whether the component choices justify the steep price. Overall reviewers lean toward the MU2 being a justified premium purchase, but some reservations keep the score below the very top tier.
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