June 14, 2024


Buzz The Music

In Barn for Review: Grimm Audio MU1 Music Player

The Grimm Audio MU1 can function as a Roon Core and Roon Ready endpoint, sending out digital audio via S/PDIF or AES/EBU to your DAC-O-choice. Seeing as I prefer to run with AES, that’s how I plan to use the MU1 during its Barn stay.

The MU1 offers four digital outputs including an LS1 Control Out for connecting to Grimm’s LS1 Active Loudspeakers, three digital inputs including USB for attaching USB storage, a 3.5mm socket for an external IR remote, an IEC inlet for power, and a tiny, little power button. Why is it tiny and in such a hard to reach place? Because you want leave the MU1 powered on and ready for action.

MU1 Signal Flow. Image credit: Grimm Audio

From Grimm:

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.

The golden circle up top is a multi-function control knob (cool!) but you can also use the browser-based Grimm app to control volume, input selection, and accessing the menu selections including Upsampling all data (2fs/4fs). Beyond the company logo that cleverly includes an activity display LED doubling as the dot on the “i” in Grimm, a centered 3.5″ full color TFT screen completes the lovely simple MU1 looks.

The review sample came with an optional 2TB SSD for music storage , which will get loaded up with most of my library. I’ve been hearing good to great things about the MU1’s performance from a number of sources, so I am very eager to get to listening. Stay tuned!

Grimm Audio MU1 Music Player
Price: $12,500 with no internal storage, +$235 w/2TB SSD storage (as reviewed), +$630 w/8TB SSD storage
Company Website: Grimm Audio



  • Max. ambient temperature for operation: 40 °C.
  • Fuse (worldwide): 630 mA fast blow.
  • Weight: 4.5 kg.
  • Dimensions: width x depth x height: 355 x 295 x 100 mm or 14” x 11.6” x 3.9”.
  • Package dimensions: 540 x 392 x 235 mm.

Clock specifications:

  • Internal intrinsic clock jitter < 0.6 ps RMS (> 10 Hz).
  • Can slave to 44.1 kHz and 48 kHz based digital sources at 1FS, 2FS and 4FS +/- 50ppm.
  • The output will mute for 80 ms when changing clock base rates.

Sample rate conversion with fpga processor:

  • Upsampling of 1FS and 2FS files, streams and digital sources to 4FS or 2FS with “Pure Nyquist” decimation filter.
    • Downsampling of DSD64, DSD128, DSD256 and DXD files and streams to 4FS or 2FS with “Pure Nyquist” decimation filter.
    • Optional FPGA volume control on Digital 1 and 2 outputs, and S/PDIF in case no LS1 is connected: from 0 dB to -63 dB in 0.5 dB (partly 1 dB) steps.
  • Latency from digital in to digital out: 11 ms at 48kHz.

Power supply:

  • Mains voltage range: 90 – 240 V AC (50 and 60 Hz).
  • Power factor: > 0.98.
  • Power consumption: Normal use 17 W, maximum 50 W.

Internal computer properties:

  • Intel i3 CPU, > 2.4 GHz.
  • 4 cores, 4 threads, with Hyper-threading.
  • 8 GB DDR4-2133 RAM 2400 MHz.
  • 1000 Mb/s Ethernet.
  • 1 x USB 2.0 port.
  • Internal SSD for OS.
  • Optional internal SSD for music data storage.

Display specifications:

  • Full color TFT LCD.
  • 3.5 inch diagonal.
  • 480 x 320 pixels.