I ordered both these and the 2020 400i from amazon to compare. I noticed immediately that the 400i were lighter so without testing the 4xx sound, I used those for a couple days. I realized after using them for at least 14 hours with leaving them playing music in between of uses to “burn in”, I wasn’t satisfied with the sound. The sound felt hollow and lifeless. Also, the headband left the top of my head sore also due to little padding and the fact that these have little clamp force, even with my oversized head.
I then tested the 4xx. Even though they’re heavier, the headband and clamp force does a good job of letting you forget about having them on. Sound wise, better than the 400i. I was left wanting more life, impact, and sparkle (but not too much since my ears ring and strain with certain headphones like the Sennheiser HD58x) and the 4xx delivered. I’m keeping the 4xx and returning the 400i.