More from a scientific standpoint and not what your ears tell you......and let's leave this to SILICONE type tips only and we are also NOT talking about fit! We are ONLY considering the sound differentiation with regards to the size of the exit hole.
On the surface I always figured a larger opening tip will always sound better or more "open"...but is this true? I have 3 thoughts on this.
1) On first thinking I would say, yes, a wider diameter exit hole (like a Westone "star" tip) will surely improve the sound over a grey flex sleeves or white tri-flange that has a smaller pinhole type exit hole.
2) But then I wonder.....no matter how large the tip exit hole is...aren't you still limited by the diameter of the exit hole on the NOZZLE ITSELF?
2) Etymotic Research may be the most credible IEM company out there in trying to achieve 100% total sound reproduction accuracy and they supply silicone tri-flanges with all their products. They apparently see no need to design a wider open diameter tip so maybe it doesn't matter???
Any thoughts? Just for reference...I have been using star tips with my W4 but I don't like the fit. My ears are different size and I almost feel like I need a size in between small and medium on one ear. A white tri-flange modded down to a bi-flange with stalk cut off to be flush with bottom largest flange fits very snug and perfect. Sounds good...bass hits hard. Logic would seem to think the the bi-tri-flange tips are better due to guarantee fit. From an SQ standpoint, would all agree????