Yeah that sounds like something's rattling inside.
Just out ouf curiosity, if you flip the DXR to its other side does the rattling maybe vanish?
That would hint at a loose cable inside.
I tried this today and it still has the same sound. Ingolf, would you be able to replicate the settings I mentioned above with your DXR10 and see if anything similar happens when you're at the volumes that I listed above? I know it won't be 100% identical due to different guitars and such. But I'm curious as to if this is just the Yamaha reaching it's peak volume levels for the speaker (not necessarily the input), or if there is legitimately something wrong with the speaker.
Also, if you are able to replicate these settings, can you let me know if your Atomic is able to handle this level of volume without any speaker issues? If it can, I just may buy the Atomic and stop messing around with the middle-tier options of speakers