Looking to upgrade from my HD 660s2 to a high end headphone. 1k-1.5k USD price range.

I currently have a HD 660s2, with a fiio k7.

I dislike headphones that are described as bright or are known for there mid-highs to highs. I'm much too sensitive to sibilance.

I also have a pair of Sony MDR-MV1 that I enjoy. I'm a fan of a smooth, bassy, and intimate sound, while not sacrificing too much on the mid to highs. I'm not entirely sure on getting a closed-back or staying on an open back, but I'm open to either. I'm also open to IEMs.

Regardless, I'd like to get my moneys worth so it should hopefully feel like a notable upgrade.