Good post @noromance
The tube sound for me has always been about the presentation, not the linearity of its FR. There is a holographic nature and weight to images that can be tough to get right with solid state. For me, if a tube amp sounds 'solid state', it means there is no real soundstage depth or weight to images - a flat sound if you will. Some tube amps do sound like that, and the opposite is true for solid state amps sounding like tube amps, but it is much rarer to find the latter.
The tube sound for me has always been about the presentation, not the linearity of its FR. There is a holographic nature and weight to images that can be tough to get right with solid state. For me, if a tube amp sounds 'solid state', it means there is no real soundstage depth or weight to images - a flat sound if you will. Some tube amps do sound like that, and the opposite is true for solid state amps sounding like tube amps, but it is much rarer to find the latter.