Found this coupon offer on TechRadar while unsuccessfully trying to find Bose's 10% newsletter sign up code, which seems a bit unreliable anyway - I signed up and received no code. The offer seems to have vanished from the Bose site anyway.
Just used to pull trigger on the Bose QuietComfort Ultra Earbuds, bringing it down to $314, and then $40 off with the Amex offer expiring in four days for a final price of $274.
Even if you don't have the Amex offer, this code still works out cheaper than taking the Bose New Year sale price of $349.95 and applying TopCashBack's 3% discount (currently the highest cashback, all of which preclude code use), which takes off just $10.50 off to make it $339.45.
Can also buy these buds (at least in black) off Catch Marketplace for $309.98 if you're happy to roll the dice with a seller called "META TRADER COMPANY LIMITED"
I was a bit put off by the frequent reports of the left earbud buzz and bad call quality but will put through its paces during the 30 day "excitement guarantee" period.
The code is unique per user and generated when clicked, so you can link to the coupon page, as the code you included will only work once.
You can see how to do that in this older expired Bose QuietComfort deal from here on OzBargain. (For transparency, it's a deal I posted and I am associated.)