I tried Sundara's after getting the 6XX I thought I was in an extremely small minority or even totally on my own thinking the Sundara's weren't that great and I had much of the same "detached" experience as you. The 6XX make me feel like part of the music, like I'm immersed in it and right in there with the band whereas the Sundara's made me feel like the music was being played at me from across the room but not in a good way and it felt like more than just a soundstage difference. Someone described them as being more "deep" than wide which resonated with me.