Hi @Fc-Construct !
Thank you for this awesome review. I know you probably dont want to be modifying/partially destroying a product you are reviewing BUT… I have been able to pair the DUNU Titan S along with the KZ AZ09 by clipping the edges of the plastic(using Hakko microcutters) around where it mates with the earbud. This allows for the 2 pins on the KZ AZ09 to have much clearance and thus sit flush into the DUNU Titan or other similar earbuds that a true A pin/B pin connection type. The DUNU Titan S + KZ AZ09 has absolutely changed my cardio sessions from meh with my Samsung Buds Plus to not too far off my Focal Elex’s at home. So worth the modification! I can share a pic of the mod if you would like