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"With the UC1, Grimm has put an incredibly high-performance device on the market. So good, and yet so incredibly versatile, that it can also be an audiophile quality DAC"

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GRIMM Audio - UC1
The Universal Audiophile DAC

“The UC1 is ​a studio device for the audiophile use ? Yup... we thought : why not. The Grimm UC1 is a true Swiss army knife, developed for the studio. But the reproduction is so good that we did not want to withhold it from you. For $5,000, you get an incredibly good sounding and versatile device. Not the easiest to use, at first glance, but oh my ... What quality !"


There are many USB audio interfaces on the market, but few of them are designed with both high sound quality and the specific use case in mind.


The Grimm Audio UC1 is in fact, by pro audio price standards, a mid price USB interface and monitor controller, but one that has a different approach.

One of the notable differences is that it It is an ideal match with the Grimm Audio LS1 or PMC active loudspeaker "monitoring systems", and works great with other active loudspeakers too. So, here we have the first notable audiophile application : A great DAC/PRE Source.


As a ‘Universal Converter’, the UC1 naturally solves all pro-audio monitoring needs. Because of this, however, it offers the audiophile user an inordinate number and variety of output and input options for analog and digital components.


Present day use cases have been the premier focus from the first UC1 designs, and onwards. This led to an unusual design with remarkable flexibility. Although of no relevance for audiophile use, we thought we'd nonetheless cover the pro-audio functionality to illustrate the complexity and sophistication of the UC1 : 


When mixing and mastering, not all inputs and outputs are equal. The UC1 offers 18 channels of USB I/O ... in "pro-audio-speak" this means 9 Left / Right channels. Of these, some are dedicated to monitoring and others to re-recording. With the second USB ‘i-put’ on the front there is no sample rate and word length restriction when using your iPad or iPhone. The "i-put" also serves as a convenient stereo USB input for laptops ... and more notably an audiophile server / streamer. One can in fact connect a second USB server/streamer via the rear USB port, and a further server/streamer via one of the two AES3 inputs ... such as the reference class Grimm MU1. That adds up to three !

How about a CD transport ? Go right ahead ... connect one into the second AES3 input using a Grimm S/PDIF Coax - AES3 cable ... as we did at Atelier 13 Audio ... and get ready for a real SHOCK ! ... And it gets better here : If you use a 'word-clock-input' equipped transport, such as one from CEC .... you can slave the transport's clock to the infamous "Grimm Clock" for even better results.

Have an above average audiophile-level Headphone ? Go for it ! ... because the key factor influencing the HP's SQ will be the UC1's perfectly clocked / timed DAC. BTW, please rest assured that the HP amplification output stage is also more than "just OK". The HP output runs through the UC1's foldback loop, so get ready for some fun : swap left and right channels ? Yes ... Mute the left or right channel ? Yes ... Listen in Mono ? Yes ... Invert polarity / absolute phase ? Yes ... By the way the USB front panel "i-put" also runs through the foldback loop... so, the same options apply here as well.


The UC1 also has analog inputs, but these are used for mastering / recording. Yes, they can be used of course, but all analog signals will be first converted by the ADC stage to digital ... and then back to analog ... not really useful, unless you'd like to try "upsampling" an LP track :=))

Lastly, we need to mention the Volume Control. It can be set to "simulate" an audiophile-typical "attenuator pot", i.e. to "zero output at the 6 o'clock position" ... or higher if you want to experiment with sharing the gain settings between it and your preramp's / integrated's Volume CTL. It adjusts gain in increments of 0.5dB.


We are currently working with Grimm on a simplified "Standalone DAC" Operating manual that focuses on use of the UC1 as an audiophile DAC. This will illustrate the "use-specific" settings required for quick and easy Set Up.

Grimm Audio UC1 features

  • 18 channel back USB & 2 channel front USB

  • 2+1 analog XLR outputs,

  • 1 analog XLR input, 1 Hi-Z 6.3mm input

  • 2 digital outputs [ 1x AES3, 1x Grimm LS1 output }

  • 4 digital inputs [ 2x USB, 2x AES3 ]

  • Versatile monitoring features

  • Ultra-low jitter clock : < 0.6 PS RMS (>10 Hz)

  • Hybrid PLL : fast lock, high jitter suppression

  • High performance phones output / 6.3mm 

  • HP specification : Max 15 dBu into 600 Ohm (30 mW)

  • Foldback for latency free monitoring

  • Chipset D/A : AKM AK4396VF 

  • Chipset A/D : TI PCM4202

  • Sample rates from 44.1kHz up to 192kHz

  • Word clock in-and output [ BNC 75 ohm ]

  • Power supply voltage 90-240 VAC, 50/60 Hz

  • Power consumption: 30 W

  • Fuse: F630 mA

  • Maximum ambient temperature for operation: 40 °C

  • Life expectancy power supply electrolytics > 45.000 hr

  • Weight: 3.5 kg

  • Dimensions: 435 x 230 x 44 mm

  • Wood type / front panel : Padauk

  • Limited Warranty : 2 yrs Parts and Labor - transferable


Grimm Audio UC1

$ 5,000

Digital Adapter Cables

Coax AES3 XLR female to Spdif RCA / 1 meter

$ 185


Coax Spdif RCA to AES3 XLR male / 3 meters

$ 235


Coax AES3 to Spdif & Spdif to AES3 adapter cable set 1 meter

$ 370

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Stand-alone DAC


Universal Converter





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Courtesy of Alpha Audio



Courtesy of Alpha Audio

... what they say ...



Jaap Veenstra | November 2021


Why are we testing a studio pro audio converter again? Or even better: a universal converter that can convert analog to digital and digital to analog.

With 1001 ways to switch it. What use is this to you – the hi-fi enthusiast? Well… that’s a very good question. The Grimm UC1 intrigued us; so we wanted to check it out and listen to it. And we’re glad we did!


There are simply put some devices that you plug in and…. it just adds up. In fact, there is very little to say about them because everything just falls into place.

And the Grimm Audio UC1 definitely falls into that category ... as do the Grimm TPM and SQM interlinks, ther Driade Flow speaker cable … and we could name a few more like that. But well: a review that just says :

"this Device is just right" … is more than a bit boring of course.


In short : we’re going to see what else we can tell about it.

A lot of Functions


The Grimm Audio UC1 is a Universal Converter. And a headphone amp, pre-amp and master clock. Damn… that’s a lot of functions in one box. True. But fortunately Grimm doesn’t believe in price gouging. It will not offer a bargain of the century, only to skimp on quality here and there. No. For €4000 (ex VAT) you buy a complete product that in fact does everything right.


To give an idea : As a DAC chip Grimm Audio has deployed an AKM 4396VF. And there are three in there (one per stereo pair). The ADC is a wonderful TI PCM4202. Internally we see, of course in a seperate housing, some famous clock crystals with circuitry. The extra housing ensures both thermal stability and it prevents resonances (the crystal is encapsulated by the way).

In one of our FLIR-image tests we did not see the clock glowing, but a heatsink doing its job. The heatsink is between the shunt regulators and the bottom plate. Thus, the UC1 is passively cooled ... and therefore it is quiet.



A few inputs and outputs


Note: this will be a long list. UC stands for Universal Converter. On the back are three sets of analog outputs: 1+2, 3+4 and 2nd Out. These can also be used as multichannel outputs. Then there is a USB input for 10 channels. Up front is another HI-Z input (line), a headphone out and a usb input (stereo) ... for headphones and laptops. Then we see on the back an analog input, two AES3 digital inputs, an AES3 output and an LS1 control port. Last but not least :

a clock-in and a clock-out. Oh, and a remote bus.



As an audiophile DAC ?


Now the question naturally arises : what is the point of having such a Swiss army knife for use at home ? We would rather ask : Why not?


These kinds of devices are made to achieve an incredibly neutral reproduction. Without “embellishment” and unnecessary expense. Think of a sleek cabinet or an ultra-modern and luxurious screen. Instead, you get a 1U enclosure (1 unit height in a server rack, about 4.5 centimeters) with only functional buttons and a menu where you, as a home user, set things up once and then don’t have to do anything except adjust volume.


The goal of studio equipment is mostly to provide maximum quality for a reasonable amount of money. It does not focus on luxury ... It focuses on quality.


And there’s a lot to be said for that, although we wouldn’t be quick to put a pair of austere studio monitors in the living room, because even in those cases, the eye also wants something to appreciate. However, the Grimm UC1 is certainly not an unpleasant device to look at. In fact, it just looks good. The ‘ears’ that we have on it for rackmount can be replaced for ‘hi-fi’ ears. And what remains is a sleek device that is quite acceptable.



Ease of use?

Well, OK ... We’ll get further into how the Grimm UC1 sounds later.

Spoiler alert … it sounds very nice… Of course, what’s also important :

How easily does such a studio converter work ?


Honestly : it takes some getting used to in the beginning. Partly because this device is not directly aimed at the ordinary consumer. There are studio functions in it that are of no use to you as an audiophile (and that you probably do not understand). For instance, consider the comparison function for two inputs. This is useful for studios, because sometimes they want to test effects. Or what about "foldbacks" (what is that you may ask ?) and routing of inputs and outputs?


You – as a home user – just want to select an input and throw it out through one output ... logical. But, that is possible ... You select a ‘monitor source’ via the menu and choose an output. This will be usually analog 1+2 OUT, but you can also control another amplifier, or set of active speakers, via analog 3+4 OUT. And then there is another one : "2nd out".  You can also select a source by pressing and turning the volume knob. Handy !


The ‘monitor source’ is the source you want to listen to. In our case the ROON streamer. And the output goes into the Bryston. So, switching the input is simply via the menu –> monitor source. Or via pressing / turning the volume knob. If you want to listen to the headphones you can just press the volume knob and ‘click’ : the headphones come on.

The Test Set-Up


Basically, the Grimm Audio UC1 replaces the Pass Labs XP-12 and the Pavane. However, we listened with and without the Pass Labs. This is because we are curious to see how good the output of the Grimm UC1 is and what, if anything, the Pass Labs can add.


As source we used the Alpha Audio PC with Mutec MC3+. The Mutec MC3+ USB sends a digital signal via XLR into the Grimm UC1. This makes it analog and thus sends it to either the Pass Labs XP-12, or directly into the Bryston 4B SST3.

As speakers we use the Focal Sopra No1. Cabling is a mixture of Driade Flow, Grimm TPM, homebrew and Audioquest. The system is connected to a Kemp HiPower 8 plus and an Isotek Titan filter. The Grimm UC1 runs on the latest firmware that was available (1.1.0).


The Sound


As we mentioned in the opening of the article, there are those devices where there is incredibly little to complain about. In this case, for 4800 euros including VAT, you get a real Swiss army knife in your listening room. A pre-amp, headphone amp, dac, adc and master clock. At a high level.



Purist device


The Grimm Audio UC1 is intended for studios looking for a versatile converter for monitoring. An ultra-transparent, high-end switch box to switch between various monitoring systems. Think two sets of speakers and headphones.


In short : the Grimm UC1 should not add any color. And it doesn’t, in our estimation. We hear – when coupled directly to the Bryston – a very complete and clean picture. Nothing distracts, nothing gets in the way. Everything feels particularly balanced. The imaging is not too big, not too small, and it is tight

and is in perfect focus.


When we put the Pass Labs in between, we don’t immediately hear a different sound, but we do hear that the Pass "puts it down" a little bigger. A little more “hi-fi” shall we say. Is that a bad thing? No, not at all ... many enthusiasts will appreciate this about the Pass Labs. To be honest, so do we.


And this feeling of bigger, and a bit more ‘hifi’, we also have with the Metrum Acoustics Pavane DAC. The difference between the UC1 and the Pavane is quite big. Especially in terms of focus. Is it good Versus bad? No. It’s more a matter of taste. The Grimm UC1 presents as being more focused; the Pavane plays a little bigger with a different kind of stage.


Analogue in

By the way, it’s pretty funny to put an analog source into the UC1. We put the analog output of the Pavane into the analog input of the UC1, and then set the clock at 192 kHz ... because we have to, otherwise it will stay silent. In all other cases it is more convenient to indicate that the UC1 has to take the clock of the source. Anyway, in this configuration we hear a lot of the signature of the Pavane. However, it is fair to say that it is not really one-to-one, although we do hear much of the timbre and focus of the Pavane. Perhaps this has to do with NOS / over- upsampling differences. What we can distill from this is that the A/D conversion is of a high level. And certainly good enough for many an analog device at home. Whether it is suitable for studio use we dare not state; we are not studio engineers. And this review deals with home use.




Now your editor is very much a fan of neutral sounding systems. The reason is simple : music should speak for itself. The engineer behind the controls makes the choices for warm, cool, imaging, placement, et cetera. A system should not do that itself. The danger is that all albums sound the same because of the "sauce of the set". And that can’t be your intention, right?


Another thing a good system brings is peace and calmness in the reproduction. A system – and the room! – that sounds balanced and keeps things tight, lets the music be heard. And no more than that. This sounds very logical ... but realize that this is quite rare ... an incredible amount can go wrong in a reproduction chain. Think of resonances in a speaker, acoustic errors, distortion in an amplifier, phase issues throughout the chain, and so on.


Now there is no perfect system (yet). Every designer has to make concessions somewhere. This may be because a certain price point must be met, or because something is not yet technically possible. And this is where the strength of a designer comes in :

  • How well can someone make concessions ?

  • How does an engineer maintain the intended quality ?

  • How well can he or she make choices ?


We believe that with the UC1, Grimm has put an incredibly high-performing device on the market. So good, and yet so incredibly versatile, that it can also be an interesting device for the home user. It sounds musical, honest, insightful, fluent, and can in fact do everything. And that is just a very big accomplishment when we look at the price tag.

And if we are being very honest : it is in fact comparable to the (more expensive) Pavane when it comes to musical quality… oef… yes… really !



For Whom ?

We can be very brief. The Grimm Audio UC1 is the most versatile converter we’ve had in our listening room. And that’s not surprising: at its core, it’s a Studio Converter. If we however "convert" it to high-end audiophile concept terms, it is a Preamplifier, a DAC, an ADC, a headphone amplifier .... and a Masterclock !


This does not make it the ideal partner for everyone, because who needs a high-quality analog to digital converter, and a Masterclock at home ? [ ...our comment on the Clock at Atelier 13 audio : We do ... with our CEC TL 2N CC Transport }


However, this makes it a device that will appeal to many fans of special things.

A person who does not go for ease of use per-sé -- because, no : it is not the most convenient device for the home user -- but a person who is looking for something a bit ‘quirky’. And with that, this enthusiast gets a super versatile device with a beautiful playback characteristic in the house. Pure, controlled and super smooth.


In short : do you like something crazy in the audio rack ? Go crazy ! :

Pick up a Grimm Audio UC1 and be surprised.




A studio device for the home ? Yup ... we thought : why not ?

The Grimm UC1 is a true Swiss army knife, developed for the studio. But the reproduction is so good that we did not want to withhold it from you. For just under 4800 euros, you get an incredibly good sounding and versatile device.

Not the easiest to use, but oh my ... What a quality ... Alpha Approved!








SQM Cables


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CD Transport w/ Word Clock 

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Mastering Buffer



LessLoss C-MARC
Power Cord

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LessLoss Firewall 
640 X Power Filter







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