@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.
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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?
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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
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@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.
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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.
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I seem to prefer using my Nucleus+ as the Roon Core on the network and fixed-volume to my MU2 as the endpoint...
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I just received my MU2 on Tues of last week, and right out of the box it sounded horrible. The bass was,for the most part, non-existent and what was there was very compressed sounding. The midrange was ok and the treble was very bright. I'm now about 20 hrs in and the bass is now present and sounding pretty good, midrange is sounding real nice and the top end is still a bit bright. It's still a bit digital sounding at times. At this point my innuos Zenith/ Denafrips Terminator 2/Audio Research Ref5 combo sounds much more natural, so I'm hoping more break in time will reveal the magic of the Grimm that everyone is talking about. I've been using the MU2 preamp and haven't tried running it through my preamp yet. I'll wait untill it's further broken in for that. I'm hoping for the best,but at this point a bit underwhelmed.
I've been reminded of how much I didn't like Roon. Since buying the Innuos and using their sense app I've found that superior, so I'm hoping that Grimm will support Tidal connect in the future and come up with their own app. I have already had a couple of dropouts, and some clicks in between tracks on playlists and that's just unacceptable and I never experience that with the Sense app. Also, I can't access my Tidal playlists that I created. Roon does.have some nice features, but the negatives far outweigh them. Just my opinion.
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How many owners leave their MU2 on all the time? I put it on standby, but then I need to backup files manually. Is it better to leave it on 24/7?
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24/7 for me. The MU2 is quite an achievement. I was an early adopter on the MU1. I’ve had various nice dacs and streamers through the years. I found the MU1 to easily best the Innuos Zenith I owned previously. Many excellent dacs (Meitners, DCS Bartok Apex, etc) have come through my system. MU2 compared to my MU1/Audio Note DAC4.1x Balanced is an interesting exercise. The $18k price of the MU2 is an absolute bargain. At this level, its a matter of what you prefer. There is a sure footed elegance to the presentation. Bass and space are strong traits. I was a die hard separates guy but those days are gone now…those who require separates today do so in my opinion because its what we’ve always done. More boxes looks cooler, the subconcious fear that the experimentation is over strikes fear…
The MU2 can be end game for most music lovers.
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@ghasley - Nice write-up on the MU2. I was very close to getting off the DAC/streamer merry-go-round and trying/buying an MU2 earlier this year, especially after reading Michael Lavorgna's Twittering Machines review, where he said,
“MU2 offers the best reproduction I’ve heard”
Maybe I should have purchased one, especially given the free delivery and 60-day return option. However, reading comments like those by @pantera2 in this thread, and by @andynotadam who prefers streaming from his Nucleus+ to running everything through the MU2, caused me to pause. I also don't like the user interface requiring volume to be controlled using a tablet. It seems that offering a simple, high quality remote should have been an easy option for the Grimm folks to include. Even an Apple remote would have been sufficient for me. I am still curious to hear one.
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@mitch2 I have no doubt that @pantera2 and @andynotadam hear what they hear and like what they like. That’s what’s fun about the hobby and we each like our food (and music) seasoned differently. Here’s my take, and its worth what you are paying for it LOL.
Servers/Streamers: I have multiple systems and I had simultaneously a Nucleus+, Innuos Zenith and MU1. I still have the Nucleus in an office system. When I bought the MU1 I was actually about to flip the credit card for an Innuos Statement or an even larger leap, to a Taiko. The dealer was one of the first to carry the Grimm at the time and he kindof whispered "I’ll sell you whatever you want but there isn’t anything under $30k that can touch the MU1". I tried it and liked it alot. The Innuos was a great streamer/server as is the Nucleus at their respective price points. Is the reason the MU1 sounds better to my ears due to optimized AES/EBU/Spdif outputs vs USB vs implementation of those very different digital feed protocols? Perhaps? But the MU1 was superior and I rolled all kinds of AES/Spdif/USB cables into multiple well thought of mid-tier dacs. I rolled all sorts of ethernet switches, ethernet cables, etc, etc....hardwire, multiple mesh setups, etc. etc. The MU1 was better to my ears at every juncture. YMMV.
DACs: There are so many wonderful dacs that have come on the market during the recent past that we music lovers should count our blessings. I’m going to forget some but I’ve had various Aqua La Scala, Formula, Lampizator Golden Atlantic, Merason DAC1, DCS Bartok Apex, Meitner MA3, Totaldac D1-Tube, D1-Six, MSB Discrete Dac with twin power supplies and ProUSB and most recently and still currently, Audio Note DAC4.1x Balanced purchased new in 2024. I’ve enjoyed them all. The Bartok Apex is terrific and a terrific value. Its network feed from an inexpensive Nucleus is about 95% as good versus an MU1 feeding the Bartok via AES/EBU. But it was even better through the Grimm MU1. The Audio Note DAC is different than the Bartok and I found them both delightful, the Audio Note being my preference after a prolonged period of comparison.
The MU2: Sonically, the MU2 strikes a nice balance between the two camps. Detail without harshness, exceptional bass, transparency and resolution while facilitating a sense of space and venue that is consistent between different recordings rather than that one goto audiophile recording you force others to endure while demonstrating audiophile cues to the person not really that interested in the dude from Columbia who plays old car bumpers. If someone is playing at this price range, people should either try it or not try it, I have no skin in the game and I’m indifferent... but to those who haven’t had an extended listen but have formed an opinion anyway? Typical audiophile tribalism, not my cup of tea.
Sorry for the long post, its just the MU2 is such an incredibly easy recommendation: A server, a streamer, a digital preamp with digital inputs, an analog preamp with analog inputs, a digital upscaler/upsampler/reclocker and a world class DAC....all in one box, that you can carry with one hand...something that isn’t mentioned very often...I’ve spent plenty of effort and $$$ optimizing my networking and ethernet feeds, too much time analyzing ethernet cables and switches. The best I found were the various offerings from Network Acoustics. I have an exceptional Network Acoustics switch that improved every combination of gear I hung off it...until the Grimm MU1 and MU2. The Grimm gear does something to the incoming ethernet feed....something positive, something that rejects the unwanted....it seem agnostic to those tweaks. Believe me or don’t believe me but none of that stuff is necessary. I have a closet full of exceptional ethernet cables (from $500-$3000) and today I just use a bog standard Blue Jeans ethernet cable. They have no effect on the Grimm to my ears.
The digital out "dilemma": I was in the same camp of no digital outs thinking I’ll just keep the MU1 if the MU2 doesn’t offer them....until you hear the MU2. Why do you need digital outputs on the MU2? You might reply "so I can try other dacs"? Well, then buy an MU1 and roll dacs, its kindof fun and you’ll scratch that FOMO itch. You won’t likely improve things, it would just be different. This TRULY is the case that the sum of the parts in the MU2 exceeds 99% of what you could assemble piecemeal and it wouldn’t be better, just a little different. Its an amazing accomplishment for relatively a steal of a price.
The remote or lack thereof: No offense intended but really? Thats a sticking point? The MU2 comes with an IR receiver. I use my iPad exclusively and occasionally use the cool dial on the top of the chassis. But the IR receiver is super convenient and it takes perhaps 45 seconds to program the MU2 using ANY remote you have or could purchase. Perhaps you have an old one laying around, or maybe an apple remote laying around, or a cool old aluminum block remote from your old Wadia....in other words, ANY remote will work. Why isn’t that a strength of the product rather than a sticking point?
Anyway, the executive summary: The MU2 is so good in virtually every way (sound quality, versatility, packaging, user interface, company support, reliability, ease of use) that if you are shopping in this price range and don’t at least try it out for yourself then you are doing yourself a disservice. Our hobby needs products like these but its hard for many to let go of old habits like three or four boxes totaling 150lbs of milled aluminum and a myriad of witch doctor umbilicals connecting them as the centerpiece to an audio shrine with one chair? An MU2, a high quality amplifier and two speakers....finally, products that live with us rather than the other way around.
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@ghasley - Thank you for taking the time to further educate me on the MU2. For context, my digital front-end is a SGC sonicTransporter i9 Gen 4, to the Sonore Signature Rendu SE Deluxe via optical, then an Aries Cerat Helene DAC. It all sounds very good but if I could have the same level of sound quality from the one box MU2, that would be a win. Also, as I read your post, it seems you are saying that I should be able to program a remote (like an apple remote) to control the volume on the MU2. If this is correct, I will definitely take a closer look.
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@mitch2 yes, the MU2 will learn the functions of ANY IR remote and you will then have an old school remote control. When the remote eventually breaks/malfunctions, any other remote can be utilized in minutes. I programmed one and...use the ipad since it works perfectly from within Roon.
You have an exceptional DAC...you should get your hands on an MU1 or a Taiko or an Antipodes to really hear what your specific dac is capable of. Then listen to a MU2...of course they will sound different and your preference should guide the way. With that said, I leave the MU2 on 24/7 so its always ready to go and no warm up required, its a no fuss product that does its job well.
I just read Lavorgna's review and he nailed it. For MOST people shopping in this price range (or higher), the MU2 is a plug and play stroke of genius. What it is not is an old school product that lets us try a bunch of different tweaks and adjustments to tinker. I'll be the first to admit, I'm a tinkerer, a tube roller, a cable roller, a speaker roller and I paused for a year for fear of that being an important part of my fun factor with hifi. I was silly to wait and I've now convinced myself I can get the same fun out of just rolling tubes in my other gear.
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So you believe it may be an improvement if I were to replace my ST i9 and Sig Rendu SE Deluxe with an MU1 to use as a Roon server/streamer to feed my DAC? Having a server/streamer in one box would be similar to what is offered by the Antipodes K50. I am curious how those two units might compare sonically.
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@mitch2 It’s a far more complicated question than the binary this vs. the binary that.
What are your goals? Whats the rest of your gear? Are you set on keeping your dac because its a great dac? Do you live near or have a realationshio with a Grimm dealer? Which input, if any, does AC optimize on the Kassandra?
I have an audio friend who tried the MU1 and preferred the Auriender N30SA. If you plan to keep your dac, then you should perhaps consider the questions I posed.
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You have an exceptional DAC...you should get your hands on an MU1 or a Taiko or an Antipodes to really hear what your specific dac is capable of.
Sounds like the combo that @tonywinga has put together. Haven’t seen a post from him lately though, and typing that didn't that didn’t show his name as one of the options in the drop down list (?) He did post reviews of both of those units (Helene and K50) in the review section.
@ghasley thanks for the input.
The Grimm gear does something to the incoming ethernet feed....something positive, something that rejects the unwanted....it seem agnostic to those tweaks. Believe me or don’t believe me but none of that stuff is necessary.
Not the first time I have read that. It certainly is appealing. How do you find the pre section compared to a separate pre- have you compared it to others?
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I leave my MU-2 on all the time.
I control volume with the svelte Apple Remote which is super easy to program to the MU2. I tried using Roon to control volume, but I wasn't really comfortable with that.
The Roon screen on my iPad shows the MU2's voIume setting as an Endpoint in the lower right corner.
I switch inputs using my phone or iPad connected over the network to the MU2 via its easily determined URL.
Easy peasy.
Break-in takes forever, and it does sound terribly closed-in out of the box...
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@mclinnguy I haven’t compared the pre section to a stand alone pre. Strangely, even thoguh I presently have several amps I slide in and out of my system, I don’t presently own a preamp.
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One thing I haven’t seen is the gain structure specs on the MU2 volume control/preamp. Is it passive, is there a buffer, or is there active/positive gain and, if so, then how much?
I believe most internal DAC/volume controls are passive. The manufacturers want buyers to believe that having sufficient output voltage is enough for good sound. Depending on the input impedance and sensitivity of the amplifiers, the cable length, and the owner’s sonic preferences, they may be right in some cases. However, there is a reason some of the DAC manufacturers offer small drive units with either active circuitry or transformers, and that is mostly for impedance management of the cables.
Considering the high’ish voltage output of most of today’s digital gear, I have been happy with a unity-gain buffer between my source gear and my amplifiers. Having the buffer interface with the amplifier restores the tonal richness and dynamics that some report missing when using purely passive volume controls, whether in a DAC or from a passive preamp.
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@mitch2
The MU2 employs a resistor based analog volume control. Thats the mild click that some hear as you increase/decrease the volume. Its a full function preamp for both digital sources and analog sources providing +8db of gain at full volume.
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@ghasley - So, it sounds like there is active gain through some form of output stage.
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It is a legit preamp. Transparent, no added sugars or salts LOL.
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I wonder about the 100k files limit. I’m not there yet with my SGC i5, but it seems likely. (Roon’s new Listen Later feature is a godsend.) What happens as you approach or exceed the limit and is there a workaround? Of course, having to periodically thin the library is not a bad thing.
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@drubin I guess if someone is dead set on having a bazillion tracks on their server then one could keep their 100,000 favorite most listened to tracks stored on their MU2 with others on another sever on their network? First world problems.
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Your Qobuz / Tidal selections count toward the 100k.
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Your Qobuz / Tidal selections count toward the 100k. I’ve assumed it’s a limit for Roon managing the database with an i5 processor.
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Assuming each track is an average length of 4 minutes, and you listened to your hifi for 8 hours every day, it would take over 2 years before a track was repeated. If most of these tracks are classical you could easily double this. I won't indicate my opinion on this.
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