I believe that imaging and soundstage are primarily impacted by the design and performance of the speakers, their positioning within the room and relative to lhe listener, and the room acoustics. The contribution from the amplifier falls far down the list compared to these factors. As @othercrazycanuck mentions, tube amps are more prone to variations in frequency response and higher distortion, which are more likely than SS amps to impact imaging and soundstage. I tend towards the school of trying to recreate the intent of the musicians and recording/mastering engineer, which suggests minimizing additions to the sound. There are as many opinions on this as there are audiophiles, however, and beauty (and soundstage) is literally in the ear (and brain) of the beholder. So if it sounds good to you...enjoy.
How Do Amps Affect Soundstage?
I'm not that technically strong on audio yet, so please refrain from mockery on this....
My DAC, premamp, and amp combo (all tube) throw a nice soundstage. If I substitute (at least some) solid state stereo amps, soundstage is constricted. If the amp is basically just increasing the signal that it is receiving from the preamp, I don't get how the size and shape of the presentation is altered materially from what the preamp is delivering. (I get that the signal could get distorted, etc.). How does the amp play such role? And do monoblocks enjoy any design advantage in maintaining the soundstage received? Thanks.