Thanks for the suggestions above! One extra thing I started to notice is that FS seems to be quite responsive to the quality of recording. I have recordings from the 90s and some more recent ones. All are stripped from CDs. I can tell that the newer albums are generally better recorded and mastered. When I listen through my other IEMs or Diana V2, the quality difference is not so noticeable.
Yes, the FS resolves hi res recordings perhaps better than anything else in my collection, especially now with some burn-in.