My new Bose Qc 35 II. I have tested both this and sony XM4 and gone with Qc35II.So much happy specially with 4.8.1 firmware. I wonder it is competing with 2020 XM4
How to downgrade your Bose QuietComfort 35 II from 4.5.2 to 3.1.8 : r/bose
Did Bose QuietComfort 35 firmware upgrade make headphones sound worse? - CNET
How to downgrade your Bose QC35 / QC35 II with firmware 3.0.3 / 4.5.2 - YouTube