What is meant when someone says a component is lacking soul

I equate "soul" being the human element of sound reproduction almost exclusively regarding vocal reproduction. 

Any instrument played by a human being can reveal "soul" as the specific musician allows their creative individuality based on their emotions to shine through in their singing/playing.

Usually by this I think of electronics which excel in some measures, like low noise and distortion but sound somehow musically thin or compressed and lacking any sense of warmth or strength. Like using it sucks the joy or feeling out.

Really good examples were inexpensive HT processors/receivers that were out around 2010.

That means it's Audio Research.