A deeper more holographic soundstage.

I was wondering by what means you have created a deeper soundstage. I am satisfied with the width but I really feel it is a bit 2 dimensional. It doesn't go back far enough. I like more layers of sound that reach towards you from the blackness.
As I've already spent quite a bit on my system I am unable to buy much more expensive components.
Did you upgrade one component that made the difference? Placement of speakers? New footers or tweaks such as Stillpoints?
Two subs instead of one(I have one)? Different placement of subs? I am working with a very tight space so it is difficult to move things without them being in the center of the room.
Any suggestions would be greatly appreciated.
If you wear glasses while listening, take them off. Primarily tightens up center image focus (in my experience) which would secondarily maximize your perceived image depth (that already exists). YMMV. Other than that, looks like you have soup to nuts options presented here. Good luck. If any of you try this and you hear any improvement, imagine how bad the effect must have been in late 70's through the 80's when the style was lenses the size of dish antennae!
Erik_squires and millercarbon both mentioned elements that improved my soundstage depth the most. Treat the area in the dimension you are trying to improve. Front and back wall treatments will improve the depth of your sound stage. The engineer at GIK made this clear. Also, using a laser to get your speakers as symmetrical as possible side to side and vertically also is an important factor to consider.
My best change was from getting a curious cable 
it became 3 d but slightly narrow and shorter image 

I read a lot of things written here as if they are gospel. I will give you my own experience.

Gospel? No. Physical reality yes.

If your speakers are two feet from the wall it's easy to calculate where you will have a null in the frequency response.

Sans room treatment it's a given echos front and back, sides may not be too bad given size and placement.

Speakers at 2 feet, 10 feet apart listening at about 12?  ... Some bass nodes at play.

Room correction?

You may very well enjoy your system but is the soundstage real or echo? Is it ideal? No.

A lot of random noise here. If you are happy with your gear and want to achieve a 3D Holographic Soundstage with scale and accurate instrument voicing, call Joe Abrams at Equus Audio. I’ve used MIT products since the late 90’s with excellent results. The new REV line Joe offers are extremely good and worth every dollar...they will allow your system to produce the most accurate rendering of an acoustic space possible.