Saying the ADI-2 FS has a narrow soundstage compared to DAC's with tube outputs is...obvious. That's the point of tubes - fatten up the imaging and expand the soundstage.
Compared to other solid state DAC's the ADI-2 FS soundstage width/height/depth is fine. Imaging is very solid, which can contribute to the perception of a narrow soundstage. But I've found that recordings with big images and big soundstages are presented as such, and recordings with smaller images and narrow soundstages are presented accordingly. In short, it's an honest DAC.
Compared to other solid state DAC's the ADI-2 FS soundstage width/height/depth is fine. Imaging is very solid, which can contribute to the perception of a narrow soundstage. But I've found that recordings with big images and big soundstages are presented as such, and recordings with smaller images and narrow soundstages are presented accordingly. In short, it's an honest DAC.