Component contributions to “sound stage”

Then room acoustics, specially first reflection points on sidewalls.

I agree with most on here, but I would like to stress that the room itself is the most important component, not just its acoustics or the treatments within, but also the available size and the placement and positioning of the speakers within. It won’t be possible to get a very deep or wide soundstage if the room is too small or too big depending on the speakers’ performance and placement. We often talk about reflections being our enemy, but leveraged and managed properly (with treatments), they can become one of our best friends.

In addition to all the components listed, I’d also like to add that the number of subwoofers of an appropriate pedigree based on the room size and shape help to clear our room modes and advance beyond soundstage limitations set by the room and speaker. 

This is not as simple as just ’the room and speakers’ though they ARE very important in the chain.

You see the entire thing from the studio and mic’ing, the sound engineering, the pressing and onwards affects the stage. Let’s say you have a jazz combo where the musicians are close-mic’ed. Then more of the "soundstage" will be in the engineers’ and producer’s hands. They will control where an instrument appears in the "soundstage". Early Beatles recordings are great examples of this. If OTOH the mics are out in the room away from the artists, then you would get more of the studio’s acoustic signature in the recording with less specific placement other than perhaps left and right. Orchestral recordings done with only a couple of mics are excellent examples of this.

Do monaural recordings have "soundstage"? 😉

NOW we get to our "speakers and room" components. I have a pair of electrostatic speakers that are very sensitive to placement, especially as regards the soundstage. Contrary to what one would think, if I toe them inwards, the stage gets wider and less focused. As a consequence, the ’sweet spot’ though wider is slightly less satisfying. OTOH, if I toe them outwards a bit, the stage is very tightly focused at the cost of having a very narrow sweet spot. (And boy do I mean narrow!)

With regards to the influence by any components, other than speakers, I would suggest that your sources (LP, CD, Digital) which read and reproduce the recorded signals followed by your preamp would influence the sound stage. And finally, of least influence will be your amplification. Why? Good amplification will affect the quality of the reproduction in the chain (dynamics, frequency response, etc) but has little bearing on where an instrument will appear on the stage.

At the risk of causing controversy, I fail to see how a powercable might affect soundstage.

Happy listening.

@musicfan2349 I totally agree that the recording and mastering process is an ultimate source of where soundstaging happens, but I don’t think the OP was intending that to qualify as a “component” in the original inquiry (I am assuming this and can be wrong). Yes, it can be a variable such that you can seek a better mastering of a particular source, but often, we as listeners don’t have control over how that is delivered to us until we put it in our room.

FWIW, I’ve heard incredible mono recordings that have incredible depth. Yes, the width is homogenous left to right, but layering is a special characteristic of mono. The Analog Productions remaster of Louis and Ella is an exceptional example of that.

@blisshifi Thank you for the kind response. You are likely quite right about the OP's intent behind his/her original question. My response was meant to get them to consider that soundstage is "set" way before the needle hits the vinyl. I suppose that subtlety was lost which is completely my fault. 😉 (Being quite sincere!)

I'll have to dig out some mono recordings of mine and give them another listen for what you are talking about regarding depth. Thank you for that!

Happy listening.