Regarding custom tips with UM3X....FYI
I have them and still prefer the star tips. Not sure if it is the type of resin but they just don't stay on and I have heard other members say the same. Even when on, I like the sound with star tips better.
UM3X nozzle also does NOT go flush up to the housing. There is a funnel flange in between which adds to the bad fit of UM56. Just saying...
But I couldn't be happier with the star tips. Using the ones with no color designation. Treble come through perfectly and bass is equal to using complys.