Grimm MU2 Experience

I have ordered a Grimm MU2 and was wondering whether an owner out there could share there experience with the unit and what to expect with break-in?


There is another forum that starts with audio and ends with style that has an extensive thread on the Grimm. 

Doesn't appear to be much available about break-in and what to expect.  Another forum which starts with What's had a thread which mentions rather extended break-in with it.

I’ve had my MU2 for about 3 weeks. All I can say it’s the best digital that I’ve personally owned and I’ve had quite a few top performers including Lampy, Dave/Mscaler, Bricasti, Innuos, Spectral CDP. All the industry reviews are pretty accurate… can listen for hour after hour without any listener fatigue ( which I’m sensitive to) and not question what your rig is doing right or wrong…….you just become engaged with the music.

Thanks very much for your feedback.  My unit is scheduled to ship from the Netherlands early next week.  I must say that I am excited but nervous at the same time.  I did hear the unit briefly at Axpona, but it was really difficult to draw any meaningful conclusions.  I will say that it sounds different and it may take some getting used to.  I have heard some stories from users about some break in being over 300 hours.  Others have said that after about a week it really starts sounding like it is getting there.  What has been your experience with break-in?

I didn’t even bother listening to it seriously the first day. After the initial 24 hours it sounded pretty darn good to me. It continued to improve modestly over the next few weeks. 



Jealous of you guys as I can’t swing the Mu2 right now. I upgraded my front end with a T+A Dac 200 for now. Long term goal is a Mu2 with a pair of quality mono blocks. 
I heard the MU2 at Axpona with a LTA integrated and can’t remember the speakers. Very underwhelming but I don’t think the amp and speakers were a good match. Too many respected audiophiles rave about the Mu2 and are replacing 30k in seperates. 
@audio_nirvana  are you using a pre amp? What’s the rest of your system?

@yowser I received the unit on Saturday.  Unfortunately, I have a terrible ground loop that has precluded any listening. 

Actually, I was concerned that the unit was damaged in transit, but I have just concluded that it is a ground loop and not damage.  I have never had any issues with ground loops or hum with the system, thus my concern that it might be damage.  I have a Trafomatic Rhapsody 300B parallel single ended amp and when the MU2 is plugged in as soon as the ICs are connected I get the hum.  Short term I am using a cheater plug on my amp, but I need a more permanent solution.  I have ordered a turntable ground wire which I will attach to the ground lug on the back of the amplifier and connect it to the chassis of the MU2 to see if that takes care of the issue.  I have the MU2, the amp, and the power supply unit for my field coil speakers on separate outlets but on the same circuit. Would prefer not to use a power strip.

Any wisdom on ground loops would be welcomed.

From what I have heard behind the horrible 60Hz hum, sounded pretty amazing.  Voices are very lifelike and the soundstaging is very precise.  I am looking forward to beginning to listen.  I am running the system 24/7 on a playlist in Roon with the amp off.  Sounds pretty good right now, but i am expecting it go get weird for the first 7 days and then start to improve through 200-300 hours.

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@wlp3 Sorry to hear that you have a ground loop when the MU2 is placed in your system!  I did a quick search on the forum and it appears that it's not all that uncommon.  I'm sure you'll get it figured out, but at least the cheater plug gets you by for now.  I have a MU2 being delivered today and is the reason I inquired as to your experience to date.  Glad to hear that it's sounding amazing right out of the box and likely to get even better after running it in.

@yowser Congratulations on the MU2.  I have had a chance to listen a little bit yesterday (20 hours), and I must say that even as green as it is you can tell that it is going to be very special.  Let me know your initial reaction to the sound.

I have the MU1 and I'm considering the MU2.  But haven't experienced one yet.  


@yowser Any preliminary impressions?  My Roon over the weekend was painfully slow sometimes buffering for >1 minute and hanging up.  Are you having that issue?

My early impression mimics yours and the multitude of the reviews out there.  Vocals are lifelike as you said, just as the music in general is more lifelike.  I remember one reviewer likened it to opening a window.  It sounded great right out of the box and continued to improve over the last 100 hours.  I've had it playing 24/7 with playlists and Radio Paradise, then listening in the evenings for 1-2 hours.  I'm impressed with the micro details in the music without being analytical.  I'm always a little skeptical of reviews, but they were so overwhelmingly positive on the MU2 that I had to listen in my home and I'm glad I did.  In answering your question, I did not have any buffering issues over the weekend.  As to your ground loop issue, I noticed on the last paragraph of page 7 of the supplied manual that Grimm states the MU2 "relies on safety earth in the mains cable to guarantee your safety. It also needs this connection as low impedance path for mains leakage current to prevent hum or sound quality degradation" and suggests consulting an electrician.