In the past two years I have purchased:
3x Bose QuietComfort 20
3x Bose QuietComfort 25
1x Bose QuietComfort 35QC
The QuietComfort 25 kept breaking down and produced a loud beep sound. The product was replaced by the store and later it was replaced with the QuietComfort 35QC which has been performing very well without an issue (great improvement).
The first QuietComfort 20 (in-ear) that I purchased has performed well for +/- 6 months and then also occasionally produced the loud beep sound. The beep sound could be undone by blowing on the bud so I have accepted the issue and kept using it, until after +/- 1 year (after purchase) the left ear also started to produce a loud noise/static which was unbearable.
The QuietComfort 20 had 2 years warranty, however, because the store had been replacing the QuietComfort 25 for 3 times, I decided to simply purchase a new one.
The second day the new QuietComfort 20 produced a loud beep sound and after a week also a static sound. I returned it and received a new one.
Regrettably, also the replacement has started to produce a loud static noise and cracking sound (very loud) after just 2 weeks usage.
I have used the headphones with great care. They have been put back into the case and haven't become wet. They have been used extensively for +12 hours per day (office) but I have no idea what could have been a factor for the headphones to break down.
I hereby want to ask support. I have the following questions:
1) is the issue known?
2) what can be done to prevent or resolve the issue?