Was thinking about the offering of the three filters on this IEM, and just an idea, related to what I've been experimenting with in my IEM listening lately: frequency response reaction of the ear changes, depending on volume, and environmental circumstances.
One simple thing that always strikes me is that my different IEMs, earphones and experiences with speakers over the years has always led to a "volume sweet spot" that seems optimal for the particular transducer I'm focusing on.
Early on, with my first IEM, I found myself turning things up too loud, due to lack of bass and balance in the default sound. As I've graduated to better/more recent IEMs, I am delighted to be able to turn the sound down, and get a good, distinct balance that lets me hear everything, high and low.
So, to my point: when you're listening to an IEM, it can be in a quiet environment, on the street, on an airplane or train or bus.
Each environment has a different effect on your perception of volume and frequency spectrum balance, even with good isolation. I noticed this early on, when the simple fact of AC turning on in an apartment or home basically killed all the sonic detail I'd be able to hear with it off. Ditto with vinyl; any distortion, noise, flutter, wow, hiss, etc. changes the noise floor so that the smaller details of the music get masked (and the transients become less precisely heard as well, no matter how well they're captured).
The filters on the SE846 seem to be, among other things, useful for tuning the IEMs for the kind of environment you're listening in. I always find bass lacking when I'm listening to IEMs on an airplane, for instance, even with good isolation; using the warm filter on the SE846 for flights, I'd be willing to bet, solves that problem. At the other extreme, wanting to listen to something very quietly usually loses the detail in the treble frequencies, the "air," even if you hear the musical elements in the 2-4kHz range. So, you use the treble filter to increase the treble frequency in the overall balance, and I bet you can listen at MUCH lower volume with pleasing high frequencies and air this way.
I'm sure the flexibility is also useful for different kinds of ears, different musical preferences, etc. But it occurs to me that the environmental factor is a big one that makes this kind of approach something that could well be a standard for all future IEMs to embrace.