What was your problem with the tri-flanges? I've tried just about all of them (including customs) and tri-flanges are the best provided you can get used to the deep insertion. I wouldn't recommend customs at all, as they'll kill the bass and make the treble peakier.

Same as Anax... it irritates my ear canal. much more than my CIEM ( silicon IEM with deep insertion too)

The friend who sold me those ER4 use only stock gray foam tips and he's a fan of his ER4 ( He had two pairs and sold me one and he prefers his ER4 to many TOTL iems like Shure SE846 for example) .  For customs tips, Piotr told exactly the contrary (  Bass increase)  and If I refer to my Custom iems (Music two) , it provides really deep insert.

I think I'll try custom tips then make my own opinion and give you the results of my experience.


EDIT :  Compared  stock complys and stock Tri-flanges. It seems Complys eat the microdynamics and some treble but helps to have more bass.  It seems I struggle to have a good seal with triflanges.

EDIT 2 : fuck !  I found a good fit with the triflanges  . bass are alive !