So, I'm spending some more time with the Sigmas. They really are an interesting headphone!

I started to think they had sort of a closed headphone sound, but then I realized (for me) it sounds more like a room that has sound treatment.  There is a spaciousness, but it's like the walls are damped.  At least that's what's striking me tonight.

Yeah! That's sort of the way I hear the Sigmas. It's like... being inside a room listening to a source, like a wall of sound but still holographic.

The Sigmas are a significant part of headphone history, because they were the first overt attempt to address the idea of spatial presentation in personal listening. Headphones were really invented more for diagnostics, listening for details in signals and whatnot. Stax wanted to make a headphone that focused on the actual listening experience, something to involve the listener more in music. Or so the story goes.

Dunno if they were the first to care so much about "soundstage," but they were definitely one of the first and most overt (or perhaps over-the-top).

By the way, do you have the Pros or the normal bias ones? There's supposedly a discernible difference, and I know those who have both tend to prefer the normal bias ones.