I ordered about 5 sets of blue filters from shure to go crazy with modding.
I found out that the baseline sound for every set of blue filters differs. Some are bassy, some are trebly, some are mid scoopy. All of this is independent of foam position. Moving the foam results in more or less treble.
The takaway from this is, if you don’t like your iems. You might want to get some spare filters. They are not all the same, there are differences between the blue ones. This probably has something to do with the filter cloth. The neater the cloth looked, the more trebly or scooped the filter sounded. The filters with a little extra cloth sticking out seem to be more bassy.
Then, add to that that I’ve listened to 4 pairs of 846. There are noticeable differences between sets as well.