Sundara is a neutral headphone, it is quite close to the Harman Target (the 2020 version, the previous one had some differences according to some audiophiles who have already tested both).

It has a very linear response between 100Hz to 1.7KHz and maintains a good amount of volume from 4KHz to 7KHz without causing hearing fatigue or major anomalies, which helps with the feeling of separation/imaging. It has a little more activity above 10KHz, which makes it look more detailed than headphones that don't have as much activity in this region.

It doesn't have a big soundstage, the Sundara doesn't have the very deep cuts between 1KHz to 2KHz and 7KHz to 10KHz, but these cuts can generate some unwanted effects, like some things sounding very distant and small.

Because of all these things, it's a pretty technical headphone, but without sounding weird or overly fatiguing.