I was going to say, most cyanoacrylates are pretty brittle. There are a few "toughened" ones that are okay for dust cap or voice coil attachments. The strongest adhesives I've run into are the acrylics. Good old Speedbonder 324 was the first. Now there are bunches.
Most of the adhesives industry has been gobbled up by Henkel of Germany. I'd suggest to the OP to peruse their site and try to find a local rep who can get back to the factory experts on suggestions. It's a good bet that JBL is using some Henkel product under one of their many brand names. Finding the right people might lead to a suggestion as to "people like you are asking about probably use something like this".