Grimm Audio MU2 "Major Dac"

I use the Soulution 725 as Preamp and MU2 is connected through XLR (Driade Flow Reference). The MU2 is Set to 85% ( -7dB) volume level fixed.

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Rgds
Gerald
@gerihifi I'm curious about how you arrived at - 7bB for the MU2. I assume you just iterated through various settings until your ears said this was the best setting.
 
@gerihifi I'm curious about how you arrived at - 7bB for the MU2. I assume you just iterated through various settings until your ears said this was the best setting.

Hi, it's a general thumb-rule (my opinion) and not put it on max - always around 85% of max volume if preamp is attached. Also see Grimm FAQ:

- This rule doesn't apply in setting done mentioned earlier, as you set the MU2 to "Fixed Volume"
- As advised with "fix volume" in roon device setup, this doesn't apply as well:

1720618438458.png

BTW: Eelco Grimm mentioned to me that MU2 nativley supports DSD up to 256 (I completly overlooked that) and they also do their magic 1.5bit instead of 1bit data conversation. I tested some DSD256 albums and I'm pretty impressed - highly recommended to test!
 
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For those who don't follow the MU1/MU2 thread on AS, Eelco Grimm responded to a query about the software update to add UPnP/DLNA functionality:

"The UPnP/DLNA function of the next big MU1/MU2 update will be JPlay and Audirvana certfied. It takes longer than expected due to external reasons I cannot comment on here, but also because this is a major firmware update that has impact on many aspects of the playback system. And also because the same software team has been working on the quite spectacular LS1 update that is currently in beta. Please keep a little more patience, we build all software completely ourselves for stability reasons and stuff like this takes time."

While I'm happy with Roon, it will be fun to experiment with the others and make a comparison.
 
For those who don't follow the MU1/MU2 thread on AS, Eelco Grimm responded to a query about the software update to add UPnP/DLNA functionality:

"The UPnP/DLNA function of the next big MU1/MU2 update will be JPlay and Audirvana certfied. It takes longer than expected due to external reasons I cannot comment on here, but also because this is a major firmware update that has impact on many aspects of the playback system. And also because the same software team has been working on the quite spectacular LS1 update that is currently in beta. Please keep a little more patience, we build all software completely ourselves for stability reasons and stuff like this takes time."

While I'm happy with Roon, it will be fun to experiment with the others and make a comparison.
I have all the things that would let me test UPnP/DLNA, I doubt I will race to try them. The MU2 with a Muon Pro System is just fine with Roon. Those other programs just don't match up to the ease of Roon. Bah. Audirvana is like a puzzle that constantly changes. Have a large DSD collection? That stops it dead cold. Bah. (At least it did for me)
 
I have all the things that would let me test UPnP/DLNA, I doubt I will race to try them. The MU2 with a Muon Pro System is just fine with Roon. Those other programs just don't match up to the ease of Roon. Bah. Audirvana is like a puzzle that constantly changes. Have a large DSD collection? That stops it dead cold. Bah. (At least it did for me)
completely agree that MU2 with Muon Pro using Roon sounds like music. Period.

A friend who uses Audirvana has experimented with many, many settings. To him, that process is enjoyable. It wouldn't be for me. I think JPLAY makes sense when used with their server because that is the reason one would by their server.

But, these additional capabilities will expand the market for the Grimm Audio products and that is a good thing. The MU1, and especially the MU2, could change the perspective about the fact that enjoyable music playback need not impose complexity on the end user.
 
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Eelco Grimm posted this a day ago:

We regularly test the output of Roon in 'Device volume' mode to make certain that it outputs the data bit-transparent. We do not test Roon in Fixed Volume mode since in the past we have seen some issues in that mode and most people like to have the convenience of controlling the volume from within Roon so 'Device volume' is more important to us. I presume those issues are solved now, but if you use 'Device volume' you are certain that we looked after it. Note that with 'Device volume' you can still set the MU1 or MU2 to fixed volume in the GRUI web interface.
On another site there was a question about fixing the volume level. Eelco responded as follows (I highlighted the part that refers to the MU2's design):

"The procedure with the current MU2 firmware to achieve a 'fixed volume' is as follows:
1. Put Roon in 'Device volume' (always...).
2. Dial in the volume that you like the MU2 to play at. It can be any volume you like, just dial it in with the top control knob or Roon's volume setting.
3. Make certain that this preferred fixed volume level is at or below '0 dB' on the MU2 display.
4. Click 'fixed volume' in the GRUI web interface.

From now on the selected volume will always be used. The sound quality is the same for any selected volume level. The same electronics is always in the signal chain, the relay volume control system is part of the DAC buffer stage. With 'fixed volume' you just fix the MU2 volume control to a certain setting. So for the shortest and most transparent signal chain, leave out an external preamp. If you wish to 'color' the sound with an external preamp, that's perfectly fine of course. In that case you can fix the MU2 volume control as described above."

I'm currently trying the Roon setting at Device Volume instead of Fixed Volume which I have been using for some time. In casual listening, it sounds great. Will need to motivate myself to do a more A/B comparison, but those aren't much fun these days. Just listening to music is far preferable. The other experiment would be to lower the fixed setting below 0dB to determine what, if any, SQ changes result.
 
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Hi, it's a general thumb-rule (my opinion) and not put it on max - always around 85% of max volume if preamp is attached.
Currently trying the -7dB on the Grimm (Roon = 85). For this experiment, the Roon volume setting = Device Volume. Will try Roon Fixed Volume too.

These are not only fun experiments, they also demonstrate the MU2's flexibility.
 
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Since the first day I hooked up my MU2 DAC I have favored its sound. I have favored it so much that until tonight I stopped using the DAC in my BACCH-SP adio. This was my previous favorite DAC. I had a passionate 3 month love affair with a Mola Mola Tambaqui someone sent my way. But hearing the MU2 I sold the Tambaqui without any thought or regret.

This week I picked up yet another pair of Stealth Audio V17 Sakra LE balanced interconnects. The same as I use to connect the Grimm MU2 to my Commander Preamp. Tonight I hooked the DAC outputs from the BACCH-SP adio to the Commander. I used a function on the Commander to match the perceived levels best I could. This allowed me to switch between the two DACs. It is surprisingly really, really close. I haven't picked a favorite yet, more study is needed.

For the Grimm MU2 setup, the MU2 streams to the endpoint in the BACCH-SP. It does all its processing and outputs a digital signal via SPDIF (Stealth Octava-T) to the MU2 and outputs to the Commander.

For the BACCH-SP, the MU2 Streams to the endpoint in the BACCH-SP and its DAC connects up to the Commander.

And of course there is the option to stream from the MU2 to the MU2 and take all that external processing out and listen to the MU2 in its pure state.

But the BACCH-SP, now armed with Optimal Room Correction as well as it's crosstalk elimination software pulls a lot of weight. It's fun to listen in different ways. For me BACCH processing always sounds best. You might feel differently.

Fun though!
 
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Since the first day I hooked up my MU2 DAC I have favored its sound. I have favored it so much that until tonight I stopped using the DAC in my BACCH-SP adio. This was my previous favorite DAC. I had a passionate 3 month love affair with a Mola Mola Tambaqui someone sent my way. But hearing the MU2 I sold the Tambaqui without any thought or regret.

This week I picked up yet another pair of Stealth Audio V17 Sakra LE balanced interconnects. The same as I use to connect the Grimm MU2 to my Commander Preamp. Tonight I hooked the DAC outputs from the BACCH-SP adio to the Commander. I used a function on the Commander to match the perceived levels best I could. This allowed me to switch between the two DACs. It is surprisingly really, really close. I haven't picked a favorite yet, more study is needed.

For the Grimm MU2 setup, the MU2 streams to the endpoint in the BACCH-SP. It does all its processing and outputs a digital signal via SPDIF (Stealth Octava-T) to the MU2 and outputs to the Commander.

For the BACCH-SP, the MU2 Streams to the endpoint in the BACCH-SP and its DAC connects up to the Commander.

And of course there is the option to stream from the MU2 to the MU2 and take all that external processing out and listen to the MU2 in its pure state.

But the BACCH-SP, now armed with Optimal Room Correction as well as it's crosstalk elimination software pulls a lot of weight. It's fun to listen in different ways. For me BACCH processing always sounds best. You might feel differently.

Fun though!

Interesting setup, but BACCH-SP and Grimm are very different DAC design approaches ;-)

I've to say, I completely stopped to play around with any kind of upsampling, room correction in my 2-way stereo setup. It is a never ending rabbit hole and distracts me from music listening (also too many sonic changes to source materials never intent to be).

MU2 is my roon core for any streamers in the house, Holo May KTE the DAC for my PS Audio SACD (I2S) & Pachanko Labs Constellation Mini SE server (have to try it with AES/EBU on the MU2 in a later stage). Abbas Audio also used for some other CD transports (SPDIF) and streamers.

No more DAC's/streamers for me the next x-years :)

Happy music listening!
Gerald
 
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Interesting setup, but BACCH-SP and Grimm are very different DAC design approaches ;-)

I've to say, I completely stopped to play around with any kind of upsampling, room correction in my 2-way stereo setup. It is a never ending rabbit hole and distracts me from music listening (also too many sonic changes to source materials never intent to be).

MU2 is my roon core for any streamers in the house, Holo May KTE the DAC for my PS Audio SACD (I2S) & Pachanko Labs Constellation Mini SE server (have to try it with AES/EBU on the MU2 in a later stage). Abbas Audio also used for some other CD transports (SPDIF) and streamers.

No more DAC's/streamers for me the next x-years :)

Happy music listening!
Gerald
I have three rabbits in my home. And rabbit holes? More than I can count. (It isn't the bunnies fault)
 

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