I didn't like harman target on the 660S as well for the same reason as you, felt like it ruined vocals. I'm using Amirm's eq (only 3 bands) and like it a lot, it keeps the intimate vocals and gives a needed bass boost. https://www.audiosciencereview.com/forum/index.php?threads/sennheiser-hd660s-review-headphone.34755/