Grimm
MU1 Review
Grimm Audio
was founded in 2004 and is based in Eindhoven, The Netherlands. Helmed by Eelco
Grimm and Guido Tent, Grimm is well-known in professional audio circles.
Grimm claims that the MU1 is the ultimate digital musical source. That's certainly a bold claim - let's see whether the MU1 performs as claimed.
Description
Underneath
the hood, the MU1 runs its software on a Linux-based Intel i3 computer board and an in-house designed FPGA board which runs format and sample rate
conversion. An ultra-low jitter clock (<0.6 ps RMS (>10 Hz)) completes
the picture. Hey, it’s a Grimm and you wouldn’t expect anything less would you?
At the
moment, the MU1 is a Roon-based solution that acts as both Roon Core and Roon
End-Point. There are plans to offer a DLNA solution in the future though. Tidal and Qobuz support are available through the Roon app, but Spotify Connect is not supported.
The MU1 is
available with internal music storage of up to 8TB. Otherwise, you can use network
storage or an external drive connected to the twin USB 3.0 ports on the MU1.
Three
digital inputs (AES, coaxial and Toslink) are provided which allows the MU1 to process external data streams, allowing other digital sources to enjoy the
goodness of the MU1.
The FPGA upsamples
the data stream to either 2x or 4x of the sampling rate before being sent to
the two AES or single coaxial digital outputs. A fourth digital output via an
RJ45 port serves as a proprietary connection for the Grimm LS1 speaker. The
digital outputs may also be configured for 6-channel output for surround sound
use. No preamplifier ? No issue – there is a digital volume control on hand too.
As there is no way to attenuate DSD streams, conversion to PCM is required to
make use of the volume control.
Setting
Up
Hook up the
MU1 to your network via its LAN port (wireless connection is not available),
switch on the power, and you are ready to go. The difficulty factor depends on
how familiar you are with Roon. As a long-time Roon user, setup was
straightforward. The well-written manual is comprehensive, and I spent less
than an hour setting up the MU1 and loading my test tracks into the internal
drive. The unit connected to the internet and prompted an upgrade to its firmware. Grimm has worked hard in the past to upgrade the performance of the MU1, so you can expect steady improvements in performance over time.
Operation
The giant wheel on top of the unit controls the MU1. With a combination of short/long presses and turning the wheel, you can access the various menu options. Most users would navigate their library and operate playback through the Roon App, whether running on their mobile phones or a tablet.
The sampling rate conversion can be switched to “Original”, “2FS Oversampling” or “4FS Oversampling”. If “2FS Oversampling” is selected, files at 44.1 and 48 kHz sampling rate will be upsampled at 2FS, while 88.2 and 96 kHz sampling rate files will be played at their native sampling rate. In the case of files over the targeted oversampling rate, they will be downsampled (e.g. 8FS and DSD material). The MU1 also supports DoP in case the user prefers to play DSD files natively on their DAC.
The USB port can also be enabled to output data, but I found it sounded inferior to the AES and SPDIF outputs when paired with my Totaldac D1-Six DAC.
Programmable
remote-control operation is possible if an external IR receiver is connected to
the 3.5mm jack provided on the rear of the unit. As I did not have an IR
receiver on hand, this function was not tested.
Sound
Quality
The MU1 is simply
the finest quality Roon playback I have heard bar none. The tone is a fluid,
almost analog-like quality with powerful dynamics and extended highs. My Roon ROCK (Roon Optimized Core Kit) server runs on an Intel i7-based NUC fitted into a fan-less Akasa Turing
chassis for fully passive cooling. The MU1 ran rings around my home rig, to the
point that the performance gap between the two was simply unbridgeable.
One very
important caveat is that the performance lead of the MU1 depends on your source
material and how you employ upsampling (or not). The lead narrows considerably
if you are playing DSD natively, or PCM
files without upsampling.
If you are a DSD fan and your DAC does not support DoP, operation will also be cumbersome. You will need to change your Roon settings to output the digital stream via the USB port, which then leaves you without upsampling. You could connect up your DAC via the SPDIF or AES output, and toggle between the two signal paths, but the routine will quickly become old. The other alternative would be to stick to the SPDIF or AES output, and convert all DSD streams to PCM – something bound to offend a DSD purist!
Coming back to the sonics, there is a certain rightness to the MU1. Bass is very tight and powerful, and piano notes have a rich solidity and realism that fills the room. The midrange is on the warmer side of things, and vocals have a warmth and richness that is creamy and inviting. This is coupled with very extended and clear high frequencies that reveals plenty of detail and air. Counter-balanced with the hefty low-end and warm midrange, you end up with a tone that is not bright at all, yet highly detailed and easy to listen to. This is not a product that plays the neutrality card, but instead takes the path of connecting emotionally with the listener.
The way the MU1 produces music is very special - music is highly energetic, yet natural and non-fatiguing. Your brain instantly registers that the MU1 is a rare and outstanding product that stands out from the crowd.
Closing Thoughts
This is a niche product. If you dislike Roon or want ruler-flat neutrality, you should look at something else. Some audiophiles would balk at the price-tag of the MU1 and insist that this is an overpriced computer server build. An audition should quickly sort that out. I know of several experienced audiophiles and reviewers that purchased the MU1 after experiencing what it brings to their system. Although the outcome would be Grimm for my bank account, I definitely want one! Highly Recommended.
Grimm MU1 Music Player
Price - S$16,000 (excluding GST and with 4TB SSD internal storage)
Grimm products are available from :-
110 Lorong 23 Geylang #06-03
Victory Centre
Singapore 388410