strange behavior with mu-so

No .... But I don't listen to Metallica�� 

It may certainly happen with some other music with a quick bass line around the same frequency than the one on Metallica's songs, but at this moment i have been only disturbed with these songs. I'm wondering if it's due to the mu-so's inner tube at the rear entering in some kind of resonance.

I've always found Metallica to sound unpleasant, doubt its your Muso's fault  I read today that a Metallica album hss the highest dynamic range tested, could it be related to that?

As i told, this problem does not appear at all on the b&w Zeppelin or the Dali Kubik Free, nor on my fiio X5 with E12A and Sennheiser ie800 but it's really obvious on the mu-so.

on http://dr.loudness-war.info/al...Metallica&album= the DR are quite normal for master of puppets and and justice for all.

i got this edition : http://dr.loudness-war.info/album/view/72592

Overdubbing is a major part of Metallica's music and does not suit a number  of different systems and speakers. I doubt Naim were given much consideration to head-banging accoustics when designing the Muso. It was made  for more "gentlemanly" music.

I tend to think that a real hifi system is able to reproduce all kind of music properly, at least without such obvious defects that i have discovered on Metallica's songs. Before testing what would be the result with Metallica, i fed the mu-so with every genre of music, from classical to jazz, pop, and many more. I've frequently found a too much enhanced bass quantity compared to my other systems, even without the loudness option activated and with the "near a wall" configuration. It tends to add a warm coloration to the music that is enjoyable but sometimes the bass quantity is a bit too much regarding the type of music played (principally with "gentlemanly" music as you said). I find that mu-so works better with especially strong bass music because of this designed bass enhancement. I tried a lot of music mixed this way and the result is extremely coherent, punchy and engaging ... apart with my latest try with metallica. I think there's an incompatibility problem somewhere, maybe a mu-so particular enhanced bass frequency and the extremely quick rythm of the song combined give this kind of resonnance phenomenon.

To be more constructive and useful, can someone who own a mu-so and who's not incommoded by listening to metallica play some tracks from "...and justice for all"'s album (the first one may be enough, but not only the beginning) at a sound level between 50 and 75 % of the mu-so's max ? I will so determine if it's a general mu-so issue or a defect with mine. Thanks.

Justice for All has a strange bass hum on my system too - cd5x/122/150.  It's the recording.

I can confirm that a track like ...and justice for all has the 'woowoo' issue you mention on mine too, especially in the bridge before the chorus. I think this is mostly down to the muso being unforgiving with bad recordings.

It may also be in part due to the system having problems with that frequency, but that doesn't outweigh the rest of the musos positives for me, I love it!

I've sent back my mu-so to the store because of this issue (which i don't have with my Dali kubik free / xtra combo) and an other issue with the USB port on the side of the muso not working properly (USB key not recognized sometimes without any reason as it's always connected to the port). 

i'll maybe reconsider buying a mu-so if these issues are solved with a new firmware or design update.

Hmmm, I'm not sure getting rid of the Muso is the answer. I've heard the same album on expensive separates having the same 'issue'. Its just a badly produced album, which gets shown for what it is on good gear!

After having listened to different other systems not having the resonance problem, i'm now pretty sure there is a physical problem in the muso causing those bad vibrating noises. I hope this can be resolved by tuning the software part but for now i'm a bit disappointed by that point, the usb port malfunctioning, the level of bass frequently too heavy and the crossover for the bass speakers strangely tuned (by example sometimes the radio presenter's voice get into the bass speaker and his voice seems denatured). Despite all the great points of the mu-so, bad ones are for the moment too much for me.

Do you mean that you set the volume control is physically at 50% and sometimes at 75% to maximum? That would cause severe problems on many pieces of kit. For some reason, volume controls seem to be designed for a usable range of around 30% of their physical limits in my experience.

Yes i tried the mu-so at a sound level between 50 and 75 % of it's Max sound level and don't understand why it shouldn't be listened this way. 

As said above your problem is most likely due to the recording characteristics of the album but something else to consider is the positioning of the Muso in your room.

I tried several configurations, principally far from walls.
I even tried using 4 vibrations absorbers from Oehlbach under the mu-so (Oehlbach 55045 air absorbers), with the same result. Despite the isolated problem with metallicas songs, i found the use of Oehlbach absorbers interesting regarding the overall sound restitution from the mu-so. I found that bass was a bit more tight and precise.