Grimm MU2 Experience

@mclinnguy - It seems the HFK reviewer appreciates the sound of the MU2 primarily for its streamer (i.e., Roon endpoint) and DAC capabilities, and then as a preamp, but he noticed improved bass and a richer sounding presentation after inserting his own preamp into the chain. He apparently did not use the MU2 as a server in his system due to Roon licensing issues.

If the MU2’s onboard DAC truly operates at the high level indicated by the reviewer, then even using it as a streamer/DAC (only) may actually justify the price. Better streamers (Innuos Pulsar and Sonore’s top Rendu as two examples) are in the $5-8K range, and really good sounding DACs start at around $10K. Therefore, the $17.5K Grimm MU2, even if used only as a streamer and DAC combo, would be replacing two components starting at around $15K for the pair, and possibly ranging much higher in price depending on the level of DAC the MU2 would be replacing, such as the reviewer’s own Pacific 2 at $27K.

It seems the internal preamp suffers from a similar condition as many onboard DAC volume controls. Even those that do not strip bits seem to benefit from active gain or an active unity gain buffer such as Totaldac’s d1-driver-sublime, or even something like the transformer based Final Drive by Empirical Audio (think Slagle autoformers). This is no different from the old passive volume control dilemma and is probably related to impedance matching with the power amp and the ability to drive cables. In my system, I would run the MU2’s VC through my SMc Audio buffer but, for me, the problem would remain that I wouldn’t be able to read the volume setting on the MU2’s small display from my listening seat. IMO, they should have offered an alternate display mode that filled up the entire screen with the numerical volume setting so it could be easily seen across the room.

Bottom line for me is, the ultimate dollar value of the MU2 is in the quality of the streamer and DAC combo and, specifically, the amount I would need to spend on a DAC to equal the sound quality of the internal DAC in the MU2. Most would be happy using the MU2’s server (i.e., Roon core) function too, although I like having my server located with my network equipment in a different room from my system components. Therefore, not unlike the reviewer, I would probably connect the MU2 to my server via Ethernet and use it as a streamer, DAC, and possibly as a preamp, although, the absence of a large volume display would probably be a deal-breaker for me wrt using the on-board preamp, even if I were to run the output through a buffer. Therefore, the final question is whether the MU2’s DAC section sounds good enough for me to give up separates and, as with any DAC I evaluate, I would need to hear it in my own system to figure that out.

As with some of you, I too am skeptical about considering a one-box solution but what really interests me about the MU2 is all the positives that I am hearing about its DAC section. In his Twittering Machines review, Michael Lavorgna said:

"If you want to hear the best digital music reproduction I’ve heard by an obvious and distinct margin, you’ll need to find a Grimm MU2 to listen through. That’s it, that’s my conclusion—the Grimm MU2 acting as Roon server, Roon endpoint, and DAC made music sound at once less processed and more fully fleshed out than other digital solution(s) I’ve had the pleasure of hearing. What’s more, the MU2’s analog volume control and line level inputs turned it into a wonderful sounding preamplifier to boot. All in one."

That is high praise. Furthermore, he mentioned:

"The comparisons used for this review included the Barn resident Auralic ARIES G1.1 (review) streaming to with the review sample totaldac d1-triunity (more info) or the Barn resident Mola Mola Tambaqui (review) through a length of AudioQuest Diamond AES cable."

Thats right, he compared the all-in-one digital solution MU2 ($17,000) and its DAC section with a totaldac d1-triunity (about $23,000) and Mola Mola Tambaqui ($13,500), which are both very nice sounding DACs. Adding to the impact of his conclusion is how entrenched Lavorgna is with his appreciation of totaldac digital converters.

I would really like to hear an MU2 in my system. Stereophile and others have also given it quite high marks. Unfortunately, it seems that a trial audition is no small thing. It appears Upscale Audio (one of the dealers carrying the Grimm line) cuts their evaluation period from 60 to 30 days for Grimm Audio products, and tacks on a 20% restocking fee, or $3,500 for the Grimm MU2 - a hefty audition fee!

@wlp3 - any further updates from the OP since your comments in August, '24?

I am thrilled with the MU2.  It is Wadax level good for a fraction of the price. Stunning realism and transparency.  The break in period is quite long >250 hours.  On my system I prefer the fixed volume setting in Roon over the device volume setting….wider and deeper soundstage with more natural feel and ambiance.  YMMV

@wlp3 - thanks for the update.

For my clarity, you are saying that you have the volume fixed in the Roon settings, and then you are using the on-board volume control in the MU2?  If yes, how do you physically change the volume except by manually turning the plate at the top of the unit?  Is there an app that allows you to control/change the volume remotely?  I guess I do not understand Grimm not including a remote control with the MU2.

The MU2 is best controlled with a tablet.  You can control the volume through a sliding bar on the control app, the disc on top, or by an infrared remote.  They don’t include a remote because most people will be using a tablet to control and volume can be controlled on the tablet.  In my case I am using the volume control for my integrated amp.  If you choose to use the preamp in the MU2 you would use the control app or buy an infrared remote on Amazon if you feel the need to have one.