Sony IER-M9 (5BA) vs. UM 3DT (3DD) with Tanchjim filter
Sony IEMs are often highlighted for their congeniality with classical music, but their latest models (now becoming a bit aged), especially the IER-Z1R and M9, are known to be very responsive from low to ultra high frequencies, so they can be played almost any genres with great finesse.
For example, when listening to jazz vocals with the M9, I am impressed by the fact that the bass and piano have a thick bass range and bring out a low-end with a sense of sound pressure. Moreover, since the range of the vocal has a clear projection while reproducing the weighty bass, the texture of the important male and female vocal range such as intonation and treble overtones are without a hint of cloudiness. If you listen to an IEM for longer session, I recommend that you experience the sound of the M9 as it provides a very relaxing yet detailed listen.
Compared to the M9, the 3DT is like a grand piano as it brings out a sense of scale and dynamics that approaches a big concert venue. This triple dynamic driver array has certain
je ne sais quoi about the sound output and configuration that allows them to be vibrant, alive, engaging, and highly expressive, yet at the same time to sound neutrally balanced with almost complete freedom from overt colourations. Switching to the M9, it almost sounds flat, lifeless and down right intimate in scale for about 2-3 mins until you start to understand, assimilate and subsequently appreciate its smooth yet highly polished tuning with excellent midrange and exemplary treble extension and articulation.
So for me, the 3DT does an excellent job of conveying a sense of real instruments performing within a real space whereas M9 does great job portraying non-acoustic instruments and vocals in a recording studio. Both can pick up ambient and spatial cues found in good recordings in an uncommonly vivid and believable way. I find them quite complimentary to each other and therefore are not in any direct competition.