I forgot to mention the headphones/IEMs I used for testing:
Hifiman HE4 & HE500, Oppo PM3, Dita Truth.
All of them sounded good, but HE500 sounded less attractive than I expected, maybe that is due to HE500's uneven frequency characteristics. Dita sounds great in low gain mode but with other IEMs you might encounter a noise as Focus was not made for sensitive headphones. IFI Match corrects this properly as per the info I got from other owners.
My main headphones are custom-made isodynamic over-the-ear Final Carbons by MaxNANO (Ukraine), but none of you know what they are (only 4 of them exist at the moment), so there is no reason to use those as a reference.)
Other owners that I know happily use their Focuses with Ananda, Empyrean and Ether CX headphones.