I've been paying more attention lately to the differences between listening with eyes open or closed.
I find myself going back and forth for a different experience. Eyes closed usually brings more effortless focus.
But lately, I've been noticing that with open eyes, the sense of space and soundstage seem to expand.
Maybe the ideal is to listen in a mostly darkened room with eyes open.
Related to this, I also find myself creating a visual image in my mind of the instruments I'm hearing with moving fingers on keys and strings. Anything to get the electronic-stereo illusion closer to reality.
This is an interesting topic.
Imo I find listening occurs on different levels, from the fully analytical / cognitive state to the sensuous plane of non-cognitive listening at the limbic level. These levels are typically an admixture, different combinations of degrees of both states. One of the regulators of such is vision.
I don't believe sight helps me listen better.
Listening for enjoyment I find my eyes closed much of the time. Visual sensory input causes that part of my brain to work more and ultimately is a distraction - and in that sense I agree with you that either focus or enrapture is simplified. At least my audio system does not move which would be even more distracting with eyes open.
My chair has wide arms and typically I have a small notebook sitting on the right hand arm to take notes for reviewing. As my brain parses what I hear into words I will write, describing what I hear. This I do mostly with eyes open but the eyes themselves often defocus - I pay less attention to the visual in front of me though I do focus on the paper when I write. There is something of a balancing act between the congnitive and non-cognitive - it is intensional as I move between listening and writing, and that makes it work in so far as it is an act of will and I rarely allow myself to lapse into a primarily limbic view.
I'm familiar with orchestra layouts and instruments and like you I will visualize an orchestra laid out before me - in my mind's eye, more likely happening with my eyes closed. My awareness moves between focusing on an instrument particularly in solo or a section of instruments such as trombones or violas, to the orchestra as a whole, as themes and melody flows across it. This too is a combination of analytic and sensuous perception.
We are, imo, vision-centric creatures - witness the posting of pictures above as explanatory devices. Our vocabulary is better suited to describing what we see than what we hear. The whole soundstage and imaging topics are done in visually oriented words along with notions such as tonal color and sound coloration.
Trying to describe sound, what we hear, without visual reference is a challenge. An holistic perspective recognizes that we also listen with our our whole bodies, we don't just listen to music, we experience music.
