Time. Unfortunately, time is something that a lot of companies in the IEM world don't seem to have; the focus seemingly on pumping out the next big release with little regard for the legacy of previous products. To the contrary, 64A's IEMs have admirably stood the test of time due to the considerable research and development the company has put into their products. Indeed, as far back as the release of the three-driver Tia Trio in 2017, 64A tells me that they knew they wanted to release a dual-driver, tubeless IEM. Four long years later, it's finally been released to the tune of $1200 and it's aptly named the Duo (1DD/1BA). 64A showcased the Duo at CanJam SoCal 2021 where I spent a couple days demoing it before opting to purchase my own unit for review.
This is a companion discussion topic for the original entry at https://headphones.com/blogs/reviews/64-audio-duo-review