Speaker size and soundstage


Question: for floor standing speakers, how does speaker size affect sound stage, bass response, and the depth of music?

I’m searching for a new speaker, and just tested Dynaudio Contour 30 against Tekton Electrons (16x18 room with cathedral ceiling). Tekton’s are bigger (48 vs 45 high, and 10 vs 8.5 wide, about the same depth) and had a much larger sound stage and greater dynamics and depth. Tekton’s as a rule are much bigger than most other brands, which can be imposing in a room, but the size must equate to a greater sound stage. 
But can a smaller tower be designed to achieve the same sound stage and bass depth of a bigger speaker? If so, what what speakers pull this off?
w123ale
Soundstage is defined by the sensitivity of the speaker and quality of materials used in construction (= engineering) of the speaker.
These 2 factors will determine soundstage.

Quality of materials is certainly a factor that I agree with, and think few would dispute.

Sensitivity?  ...as it relates to efficiency? I’m going to need some help understanding that one as an influence on the soundstage.
Imaging is determined by the fidelity with which extremely fine and subtle details are reproduced. Sensitivity is by definition the response to an input. The lower the sensitivity the more power required for any given input, the less sensitive the speaker. Since the magic of imaging resides in low level fine detail it stands to reason the low sensitivity speaker is other things being equal at a disadvantage. Other things never are equal, but to the extent they are, there you go.
Sensitivity is by definition the response to an input. The lower the sensitivity the more power required for any given input, the less sensitive the speaker. Since the magic of imaging resides in low level fine detail it stands to reason the low sensitivity speaker is other things being equal at a disadvantage. Other things never are equal, but to the extent they are, there you go.

Thank you for taking the time to explain it. The theory makes sense. The old Spica TC-50 comes to mind as a possible exception. I think they had a sensitivity rating of like 83db, but were well known as sound stage titans.
I have a similar question, although rather than physical size it refers to setting the speaker “size” in the receiver. 
I’ve always read setting speakers to “small” regardless of their physical size helps the receiver integrate the subs more readily. 
Is this true — and how would that affect imaging?
Imaging (millercarbon) and soundstage (OP) are two completely different things.