Of course I should have said very clearly ***in my experience *** (Edit: hmmm. That is exactly what I said). As an example the spinfit 145 I have, to my ears/hearing, brighten up the sound of the DM6 and Kanas Pro sets that I have. I will try to check my other new tips against a few of my iem sets with wide openings (DM6, KP, and MD+ for example, but won’t get into listing so as not to offend) to see if that is consistent, or if with more testing I change my mind.
Not surprised by your reaction, though. On DM6 thread, for example it has been reported that wide tip openings enhance bass/reduce treble or narrow tip openings reduce bass/enhance treble of that set. Seems very user dependent. I wouldn’t be surprised if your experience were different, nor would I be surprised if it were the same.
And, of course, cannot rule out the effects of tip insertion depth, and quality of seal.
(Edit: I haven’t experimented with this, but I assume there may be a relationship with the bore size of the iem - narrow bore IEMs like Shure and Westone may be less impacted by the tip opening size than wider bore IEMs like the Kanas Pro... further food for an experiment)
But, to my point, for those tips I did try on the DM6 and KP, definitely that was MY EXPERIENCE. Your experience, my dear sir, could be quite different, and upon more experimenting my own opinion may change, or be reinforced.