Getting to the point, I like to feel the bass, not only to hear it (just like in real life, where e.g. you can hear very low freq noise when something very heavy is dropped to the floor). In fact, I usually tolerate better bass excess than lack of it, but I like it always to be near to track reference and don't like at all when it's bloated or too exaggerated.
Extension should be good at both ends because I like air and some spark too.

Regarding mids, like them defined, a bit forwarded and natural (not too thick, not too thin neither). Love space feeling, separation and a good positioning of every sound, but timbre and tonal accuracy are, for me, at least as important as all the rest.

Love when instrument and voices sound as they're supposed to sound with realism. Like detailed textures and microdetails too, and all of that is not easy (cheap) to feed with good gear. With years passing, I discovered myself listening to music a lot doing 'zooms' on the desired voice/instrument/sound and trying to perceive it the best I am able to. But apparently opposed to this, don't like at all pure analytical stuff because I listen a lot to metal/rock (most of the time at high volumes), and balanced or bright signatures are not the best match for it. Regarding signature, I always look for musical but correct ones. Prefer it as much "all terrain" as possible to listen to all genres on the go or at home.

The last 2 years I've been fully in love with the LZ A6 and the NCM NC5v2, but now NCM Bella v1 have stealed my heart! And Bellas do all stated things more than well at least, so only will look to other IEMs for a real and big improvement or out of curiosity. In fact, I proudly own a good and varied collection under 200€, plus few higher models, but ended using most of them only to reset and compare from time to time, or when in need for something different because I like to have a daily nice gear with not too rotation.

Regarding gear, I think that the first thing is to have a decent source. No need for 500+ DAP, DAC... I'm pretty happy with ES100 and more with E1DA 9038s).
So IMO, after a good source, next is to have a decent pair of phones. Last for me are cable and tips.

Finally, I use Poweramp for wav and flac files, and Tidal Hi-Fi for the rest. Thanks for reading!