I haven't written the review yet - I wanted it to be a proper review after getting to know both, not just a list of first impressions
They are both very detailed but their presentations are quite different from each other. The 8.A gives you just about every single bit of sound present on the recording but you have to listen for it. A relaxed presentation that I can enjoy for hours (they get 6-8 hours in my ears every single day) without fatigue. They never get as mellow and laid back as my HD650, they just strike a perfect balance for my needs and taste. The 8.A lets you lean back and relax, the 4.A(i) is another beast. It serves up all the details for you on a silver platter, forcing you to listen actively and focus on the music. Keith Jarrett's Köln Concert is amazingly good with the 4.Ai, so much detail, spatial information and a stunning sound of the piano. It feels like you're really at the concert, hovering 50cm above the piano. For rap, dancehall and electro I prefer the 3.Ai or my 8.A as they both extend deeper than the 4.A(i) and have a better bass slam. Oddly, I find myself reaching for the 4.Ai when listening to the album "All Drums Go To Hell" by Two Steps From Hell. An album with - you guessed it - lots and lots of drums. You know that track "Mombasa" from the Inception soundtrack by Hans Zimmer? The one where Leonardo DiCaprio is running for his life through Mombasa and there's just percussion everywhere? Yeah, imagine an entire album with just that. Back on track: The 4.Ai is very fast and accurate so while the 3.Ai extends deeper, I really like how the drums sound from the 4.Ai. Or I can reach for the 8.A and get the best of both then the price just tripled...