I got my replacement keyboard yesterday and, so far, so good.
I used it for about 30 minutes with music playing while I played a card game app that, when active, seemed to exhibit significant random mutes with the previous keyboard. No muting with new keyboard.
After recharging a low battery, I used it for about 1.5 hours with music playing, doing various other tasks (news & weather apps, desktop & Office activities, and other game apps that had significant random muting). Again, no muting with new keyboard.
However, I did have an issue at one point with the keyboard apparently not being recognized about half-way through the second session. I detached and reattached it and it worked again. Hopefully I haven't traded one problem for another.
I didn't have the issue with the original black touch cover, but I picked up a new Cyan Limit Edition Skulls Touch Cover and it appears to happen with a gesture that is similar to two finger scrolling...
This is happening to my SP2 with a white Touch Cover that I recently picked up. My go to keyboard is a Type 2 but when I know I will mostly be mobile and not doing much typing I prefer the Touch, especially the original as it folds back really well. The random mute wasn't bugging me too much until today when the audio was muting during Man City vs. Sunderland without my even touching the keyboard.