I usually used Z1R with DAPs, but today I am listening at my home with desktop setup, I am Wowed again, Z1R indeed scales with the source. I almost felt that it can compete with my Atrium or HE6SE in some sense.
After I bought Z1R, I have demoed most of the TOTL IEMs, and only recently I also demoed for a week the Fir Audio frontier series, including XE6, KR5, and NE4.
IMHO, Z1R is still absolute the TOTL IEM, the preference within TOTL IEMs is purely personal, all the rankings are only for the creator's personal preference.
What Z1R stands together, are majority of the modern IEMs, including XE6, Odyssey, EE EVO, UM Mest Mk2, etc. I would say choosing one of them will not make day and night difference. I know someone will tell me there is a huge difference among those IEMs, but for me, they are warm, bass heavy or with very good bass IEM with TOTL technical performance.
Then there are two other slightly different types of IEMs: reference/treble focused, and colorful Mids focused. The reference/treble focus is like U12t, to slightly less reference such as Ragnar, or even Trailli and Jewel. They are extremely detailed and TOTL in resolution, but the reference tuning, or treble is not my type of IEMs, I tried very hard to demo and understand why people like them, I guess my only conclusion is they need longer time to be appreciated.
The colorful Mids are UM Mason FS, Multiverse Mentor, and probably some VE IEMs (I don't have a good memory of VE IEMs that I demoed, just from others' review. My vague memory was VE IEMs' Mids is not similar, or at the same level of my liking in Mids). I really like those IEMs, but unfortunately, I can't justify pay $4k+ to buy them.
Therefore, for me, I am more and more convinced that there is very few IEMs that I really need to have beyond Z1R.