Having the exact same issue. In the first night they were completely silent, but at the 2nd or 3rd night they started to have a really annoying background noise whenever I was playing a Bose sound.
It is some faint, high pitched twitter, sounds a bit like a cricket but with a frequency of 5-10x per second. It is not loud, but it's definitely noticeable and focusing on it is enough to drive you insane.
I even exchanged my first pair with a new one but it's having the same issue, tho it twitters a little bit less than the first one. If it keeps doing it I guess I have to refund them. God **bleep** it
Please don't assume that replacements don't work. They do. For many, many people including myself. And Bose' customer service gets an A+ in this regard for the speed and ease in replacing the buds for free.
I understand many of you have had recurring issues, and I do sympathize. But lots of folks are getting and can get great benefit from these buds, so dogmatically rejecting any solution as futile isn't helpful.
And yet the fact remains that if replacements don't work then......
I'm down £229 and Bose agreed they have no solution to offer. Thanks for your insight.