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.
Key Features:
- Roon Server integrated (up till 100k tracks)
- Ultra low clock jitter
- FPGA based discrete Major DAC
- All sample rates and formats supported
- Relay based analog volume control
- Digital AES, spdif and optical inputs
- Analog XLR and RCA inputs
- Analog XLR and RCA outputs
- Headphone output
- Web control of setup via any browser
- Infrared remote control
- External USB and NAS storage, optional internal SSD
- Tidal and Qobuz support
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. The MU2 has 2 stereo analog inputs and 3 stereo digital inputs. It has outputs on XLR and RCA, and headphones jack.
The MU2 includes both RCA and XLR outputs and perhaps less expected RCA and XLR inputs which means you can connect your phono stage to the MU2 and use its relay based analog volume control turning the Music Player into an analog preamp to boot! There are also 3 digital inputs (AES, Coax S/PDIF, Optical), an Ethernet input (no WiFi here), a USB Type-A slot for adding USB (music) storage, and a headphone jack. Full function
That silver wheel up top offers a number of functions including volume control, mute, input selection, Line / Headphones out toggling, and access to the MU2’s menu system. For anyone interested in the fine print. I preferred controlling all playback-related functions using Roon on my aging iPad or iPhone with an occasional peek at the MU2’s rudimentary browser-based interface..
All in One
When using an all-in-one device, you lose the ability to use a different DAC streamer or digital cable. That is the drawback, and I have heard significant sound changes when using different digital cables/DACs but less so with streamers. The strong point of the MU2 all-in-one is the synergy of all the components, which were crafted to play together. This allows you to play with power amplifiers, interconnect cables, and speakers, which has been more fun. When listening to the MU2, I felt no need to change functions like a preamplifier because the MU2 sounded so good.
Preamplifier
Grimm says the preamplifier in the MU2 “has a unique analog audio signal path that is Class A throughout, with a focus on ultra-low harmonic distortion and ultra-low phase modulation. The relay-based analog volume control lets the user control external analog sources equally well as digital and internal sources.” The preamplifier is quiet, and I did not feel I was losing anything over my reference LTA Velo tube preamplifier.
What makes the Grimm MU2 different?
What makes the MU2 different is the in-house engineering. Grimm created noise shaping and filtering technology to allow the micro details and fullness of sound to come to life. To explain, digital signals arrive at the MU2 and are upsampled to 8 times the base rate PCM (with many bits) before being upsampled to 128 times the base rate and 1.5 bits. Because of the low bit count, this second upsampling step creates a lot of wide-band noise, which needs to be shaped and filtered. To accomplish this, Grimm engineers developed their own discrete 1.5-bit 11th-order noise shaper, which manipulates the noise so that there is less of it between 20hz to 20khz and more above 20khz. This noise shaper remains stable, unlike most noise shapers that function differently depending on the frequency. Grimm shows the stability of their shaper in graphs included in their White Paper.
The shaped noise goes through another Grimm creation, the “Pure Nyquist” filter (read about it here). The resulting data stream goes into a 16-cell per channel DAC. All coding was done in-house by Grimm, which gave them total control over the operation of the MU2 to achieve the sonic results they wanted. They can also update and troubleshoot the software should there be a problem. The MU2 has a support setting that allows Grimm to connect to the MU2 software. See the links below to get more information on these innovations.
In the Box:
- Media Player
- Manual
