Bose are lying - QC35 II ANC is not the same as previous firmwares.
You might have noticed the numerous QC35 complaints about how the active noise cancelling is weaker since the latest firmware update. When I tested these headphones out at the store, I was amazed by the ANC, like I was in a soundproof room - was like magic, had to get it. Cut to a week later, I stupidly updated my headphones using the connect app (as it just starts it automatically, and who's going to check online if an update will practially reduce the cost of your kit by about £200).
So went onto support, usual copy paste answers we see here time and time again (I bet I'll get one on this thread too). Of course no fix, only fix is to revert back to when the firmware was utilizing the hardware properly. No, you can't revert back - why? who the hell knows. Support told me over and over that they did not change anything on the ANC throughout the updates - hard to prove it to them but they know wha'ts going on, they just won't take ownership. I have a feeling they are degrading the quality of these headphones so you upgrade to the new 700's etc, apple do it, why not Bose.
My wife got a new pair of QC35 II and I could finaly test the differences between firmware 2.5.5 and 4.3.6. Night and day! Wife's headphones got that magic quality, the reason I bought mine in the first place - my 4.3.6 cans? has that irritating white noise, hardly any ANC (low and high sound the same).
Contacted support again about my findings and they just said they'll replace my headphones - great! new heaphones, old firmware, lets party. Nope, got heaphones with the latest firmware (I think I got someone elses that returned it for the same reason) and I'm now stuck with £40 headphones that say Bose on the side. Nice. So only thing I'm hoping here is enough complaints will show Bose we want to have that magic back, but I really doubt it. Should have gone with Sony, but Bose do have that comfort... at least you can't break that with new updates.
phew, sorry about the long read.