I had what could have been a similar problem with my x2 7200s connected directly to 808.2 by Cat5. That began about 18 months ago when the 7200s were first released. Suddenly there would be loss of volume and an overall rarefied sound for some seconds that would correct but eventually repeat.

Problem solved when the electronics in one speaker was completely replaced. However, sometimes since I wonder why sometimes the sound seems to be coming form only half of the L to R field.

Meridialien it is also very worrying that your direct contact with M about the problem HQ now ended.

The more I hear about such problems and the difficulty/delay of the resolution the more I worry about M gear.