Grimm MU2 Experience

Looking forward to it, now.  Thanks for your experience.

Thanks, I will check it out.   

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.

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?

@benzman Zellaton speakers.  I agree.  It was not a well matched 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.

@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.

@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?

@ja_kub_sz   I would encourage you to experiment with the device control vs fixed volume setting in Roon.  I have found a significant difference between the 2 settings.  I have found the fixed volume setting in Roon along with the volume fixed at +0.0Db in the MU2 to be best in my system.  The fixed volume setting in Roon offers a wider deeper and more engaging experience in my system .  Of course YMMV.  Also need to note that it seemed to take quite a period of time for the unit to break in and sound its best.  I have had it in my system for about 2.5 months I think it really just seemed to really blossom lately.  FWIW

@ja_kub_sz   In addition to the volume control on the MU2 there is a setting for Fixed Volume or Device Volume in Roon.  This is accessed by the volume control icon to the right side of the music selection window on the bottom of the screen.  Select the gear icon on the menu.  Under Audio Device window hit the Device Setup.  Under the Volume Control drop down you can select DSC Volume, Fixed Volume or Device Volume.  Device Volume will communicate volume instructions to and from the MU2.  The Fixed Volume control will send a fixed signal to the MU2.  Volume can still be controlled in the MU2.  I am using an integrated amp, so I am using the fixed volume (line out) setting on the MU2, and I have selected +0.0 db as the level of signal output to the amp, and controlling the volume with my integrated amp.  Alternatively, you could set the volume on your pre-amp or integrated to a set level and use the volume control on the MU2 to control volume.  Although the gain on the MU2 goes to +8.0 dB, Grimm advises that there may be some distortion on the higher gain settings, so +0.0 dB is the recommended maximum setting on the MU2 which when Device Volume is selected equates to 92 in Roon.  On my system, using the Device Volume setting in Roon produces a more forward presentation but very detailed.  The Fixed volume setting in Roon on my system produces a wider and a bit less forward presentation but still preserves the incredible detail that the MU2 produces but with a more natural and engaging sound to my ears.  I have been flipping back and forth between the 2 settings.  I do like the Device Volume but it is more HIFI sounding on my system than the fixed volume.  Give it a try on your system.  I am not sure why there is a difference between the 2 settings but there certainly is on my system.  I am running a Trafomatic Rhapsody integrated amp and Wolf Von Langa Ultima 12739 speaker.

@ja_kub_sz   Thank you.  Give it whirl on your system and see what you think.  You may prefer the Device Volume setting in Roon on your system.  On my system, the WVL speakers are so revealing and transparent that the Device Volume setting seems a bit etched to my ear, and the Fixed Volume setting is more natural sounding.  Again, YMMV.  

I must say that the MU2 has taken my system from excellent before to ethereal now.

@ja_kub_sz The MU2 just keeps getting better and it has taken 2.5 months for it to really blossom on my system.  I think you will find that bass and hf will get even better with time as well.

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

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.