Component contributions to “sound stage”

Speakers  placement     

Acoustic treatment

Synergistic Research FEQ Carbon  Frequency Equalizer

I have a CD that is produced specifically to test the placement of your speakers.  Sorry I can't give you the name as I'm not at home for a couple months.  This recording consists of a dozen tracks with explanations of what instruments you are hearing and exactly where you should be hearing them.  It's proof positive that the sound stage is in the recording.  Sure your equipment can play a part in the enhancement of the sound, but you can't reproduce something that's not there to begin with.  Since the recording is designed to maximise speaker placement, it would stand to reason this is the place to start?   

Very good question...

I would say speaker placement (back wall, rear wall, toe in/out) seating position are probably the most important. Of course, recordings and components all contribute to soundstage.

The recording.

All your components and the recording.