Grimm MU1 Streamer - Really "The Best"?

I've recently become interested in the Grimm MU1.  While reviews of top end players from Innuos, Aurender and Antipodes and others are typically all very positive, the tone of the many pro reviews of the Grimm MU1 go far, far beyond, with some reviews resorting to using superlatives and gushing of positive system transformation and not being able to stop listening to material, etc..  HiFi Advice and Steve Huff (actually calls it "magic") have such reviews.

Given the delay in availability of the Innuos Pulsar which I'm told will be better than my current Zenith Mk3 + PhoenixUSB reclocker, I am interested in replacing my streaming setup with a one-box solution that includes a high-precision clock.  The new streamer will continue to feed my Gryphon Diablo 300's DAC module, which I have no interest in replacing.

I'm actually a fan of Innuos, after they improved the sound of my Zenith with firmware updates and after I added their PhoenixUSB reclocker. I appreciate this commitment to improving sound quality which is why I was so interested in the Pulsar.

The trigger for considering an upgrade is not for improved sound, but rather, to solve some issues I have with too many Audioquest power cords coiled and clumped together. I will get to lose one of them and one of my USB cords with a one-box streamer. I've noticed my sound is very sensitive to positioning of my AC cords and find I often need to re-adjust the PC feeding my amp to get proper sounding vocals at center stage.  One of my subs also seems to be picking up AC noise when the crossover is set above 60Hz. The second trigger is simply system simplification, removing one box.  All that said I don't really have any complaints regarding sound, and the PhoenixUSB reclocker truly did improve the sound of my Zenith.

While the Grimm MU1 has it's 4X upsampling up it's sleeve with reviewers absolutely glowing over this feature and it's extreme ability to separate tones to the left, right, front, and back far better than the rest, I don't see that Grimm has gone to any lengths with regard to power supply management in the way other brands do including Innuos. The MU1's ultra-simplistic interior doesn't bug me, but the lack of transformers and power management makes me wonder....

Are there any updates from folks who have directly compared the MU1 vs similarly classed streamers from the competition?  Did you find it to be as revelatory as the pro reviewers found it? And, how does it compare to other streamers with it's 4X upsampling disabled?  Does it sound like it suffers from it's lack of power management?  I do see that the clock should be very good...




Some developments, close to the end of this particular journey… I’ll say this right up front in case it gets missed below, but with my upgraded cables my Innuos PhoenixNET pairs beautifully with the MU1. With the new cables the PhoenixNET does not “overdampen” the sound like it did when I was using the basic cables. Here is where I am at:

  1. My Shunyata Omega AES and Sigma V2 XLR cables arrived, and have about 110 hours on them. Burn in was needed; things sounded good at first but vocals were a tad “canned” sounding. All better now.
  2. Compared to my prior entry-level temporary cables (Old green Cardas AES cable and Audioquest Red River XLR interconnects), the sound has really relaxed and opened up. High frequencies are coming through without being forceful or drawing attention - they are simply there, in a very relaxed way.
  3. Sound is more “suspended” now with far better positioning, space, and air - especially with vocals.
  4. The MU1 has more than caught up in one of the areas I thought my Innuos setup was doing slightly better in. The MU1 has become more expansive and open with a bigger sense of presence and scale.
  5. Midrange is more relaxed and expressive with more finesse. That hard midrange impact I noted previously is toned down, and in retrospect is not missed. This is better!
  6. This one is interesting. Before, I noted that my PhoenixNET didn’t pair well with the MU1. The sound was over dampened, and became dull and lifeless. This is not so with my new cables. It sounds awesome - tightens and clarifies everything without losing anything at all now! Not sure if there is any concern that the MU1’s network speed is 1000 Mbps while the PhoenixNET is limited to 100 Mbps. I will ask Grimm if this holds back sonic performance at all.
  7. Another interesting one. Before re-adding the PhoenixNET, I have to admit I wasn’t sure about the MU1’s oversampling modes. I was finding that on some tracks, vocals at center stage were not as solid and well-formed with 4X oversampling engaged. But after reintroducing the PhoenixNET, this problem went away! 4X oversampling sounds fantastic now in all cases, to me! More open, cleaner, more suspended feeling, with more space, and vocals are just as solidly formed at center stage now.
  8. As an aside I tried some sonic stabilizers that rest on top of your gear. Herbie’s. They changed the sound without a doubt. But not in a good way - sound became more condensed and compact. Will not use them.
  9. I did some comparisons feeding my original Diablo 300 DAC module using the Shunyata Omega AES. And it sounds truly fantastic! Had I tried this originally I would have been happy with this. But the Tambaqui is better - more detail, more precision, more expressive. But taking a step back, between the cost of the Tambaqui, the cost of the Sigma V2 XLR interconnects, and the future cost of a Dragon power cord, I’m not sure the value is there, considering how good the Diablo 300 DAC module sounds now that I have a premium AES cable. But the Tambaqui is without a doubt better, and since I already own the Tambaqui and XLR interconnects, I’m happy with them and they aren’t going anywhere. Debating whether to remove the DAC module from my Diablo300 amp, for a possible boost in quality due to less electrical noise in my amp.

Regarding the SR fuse for my Innuos Zenith Mk3, my dealer has not followed up twice after they had emailed they would. I’ll take that as a sign and give up on that. I may try SR purple fuses in my MU1 and Tambaqui in the future.

Regarding the Muon filter, now that the PhoenixNET is back in the mix, I won’t be going the Muon route. The PhoenixNET does filtering AND it is a reclocker for Ethernet.

As a very final step, I will be ordering a Sablon AES cable. Just have to hear this cable after several reports comparing with Shunyata, the most recent being from @svenjosh.

Really happy with where things seem to be settling out. It’s finally time to say goodbye to my beloved Innuos Zenith Mk3 and PhoenixUSB, and AudioQuest Diamond USB cabling. I can now remove the cellophane screen protector from my MU1 - it’s definitely here to stay!

My next upgrade (because yeah…) will be swapping out my Audioquest Hurricane power cords feeding my source equipment for Dragons. I currently have Dragons feeding my amp and Torus isolation transformer. Seems like a logical next step to me! Will not be anytime soon, will take it slow for now, aside from messing with the Sablon AES….




It’s great to hear that things are settling and you are enjoying your journey. I compared the Mu1 to two major streamers. I can PM you my thoughts. I do not want to derail your thread.

Back to the MU1. A point I forgot to mention, is that I find both the generic power cord that comes with it and also my Audioquest Hurricane to be looser in the MU1’s power connector socket than with most of my other gear. The slightest nudge will cause a disconnection of power. I absolutely notice an improvement in sound when I reposition and recenter the connector.

Am ordering these to solve the problem. Shunyata ships these exact inserts with their power cords to help with fit when needed.  Perhaps Grimm should too.  Have to order 100 but hey I’ll never run out.



Some use plumbers Teflon tape and find it works well. It also has an infinitely lower cost. Regards


BTW - great wrap up!