I mentioned earlier that I’d attempt to illustrate what I hear from the HEDDphone in terms of it’s rendering/projection of stage, and imaging/spatialization within that.
Here’s a simple graphic that shows what I hear vs. the Utopia, MySphere and SR1a:
The Utopia has a narrow, shallow, projection. There’s very little depth to it, beyond where the image forms relative to the listener. This is very intimate staging. For the most part it is not possible to discern depth-wise location - instruments essentially appear distributed across a curved plane.
The HEDDphone has a much wider rendering, and as a result lateral localization and separation is much more apparent. The sound can appear to come from well outside the head/headphones. Instruments are rendered closer than the Utopia, but with a little more depth. It is still not possible to localize instruments or performers in terms of how deep in to the image they are, or whether one is in front of, or behind, the other.
MySphere has a similarly wide lateral throw to the HEDDphone, but adds clear depth-wise cues that make it apparent when one instrument or vocal is in-front/behind another. It also projects further from the listener.
SR1a - shown here with the drivers set at 45 degrees (having them wider broadens and somewhat deepens the image). The image is the widest, and the deepest, sits further from the listen and clearly lets you hear depth-wise cues and locate instruments and performers both front-to-back and side-to-side. Not quite to the same level as a well-setup near-field speaker rig, but the closest I’ve heard and unique in the headphone space.