The pairing of the amp with the speakers matter more generally than the amp itself...For soundstage... ( for bad amp exist too )
But the main central factor is the pairing speakers/room if by soundstage we means not only differential imaging and the soundstaging measured apparent dimensions but also 3-D holographic volume for each instruments...
Also on par with the relation Speakers/room will be the recording itself... All recordings played on an audio system did not give rise to a soundfield filling all the room in front and behind the speakers and around the listener...Some recording lack lateral presence or in detph differentiation, some others put the sound more out of the speakers laterally and not in front of us too etc... i experienced all possible soundstage dimensions in my room... Thisc differ from recordings to recordings...
The choice of dac and the choice of the amp import less than the total synergy between them and with the speakers/ room acoustic... the speakers/room acoustic pairing and coupling and the recording state of each album being the two most impactful parameter after the synergy between amp and speakers which is the less important factor but without it nothing will work well...
At the end not all factor impact the same but each one of them matter...Nothing impact so heavily than acoustic , but if the synergy between speakers and amp is not optimal, you will not be able to correct it with acoustic...