Dual 3.5 at the moment is compatible with AFAIK the pono, PHA-3, TA-ZH1ES and not much else. XLR4 is a slightly more widely adopted standard. Sony's new 4.4mm TRRS standard is supported by the newest high end Sony gear and is compelling as a form factor but not widely adopted, although it makes more sense than anything else physically IMO
I've personally adopted dual 3.5 myself in any case, because I have over a grand invested in cables for it. But not everyone needs to repeat that now that 4.4 is out. But good god it sounds amazing. Talk about bringing new life to the HD600, lol.