What is meant when someone says a component is lacking soul

Recently had a glaring example of this when I sent my amp away for extensive modifications/rebuild and pulled out my slightly modded Adcom 555 back-up amp.  Gave it a couple weeks to come to life but never happened. What I wasn't hearing was any note decay, any hall sound.  The notes played but that was it.  Dynamically, it was like going from a Bosendorfer to a garden variety harpsichord.  No ebb and flow to the music!  No "life".  Or you could call it a lack of "soul".

To paraphrase Issac Hayes: Fresh hot popcorn without salt and butter.

 In my circle I might say of great sounding and feeling music playback "Man, that's filthy!"

IMO, "lacking soul" means flat or blurred dynamics possibly accompanied by alack of transparency and / or harmonic detail.

True musical detail is most often a matter of electronics that possess very accurate timing.  

It does not have to sound clinical or uninvolving to lack soul.  I build a DHT preamp that has a selector switch so you can use five different resistors.  Each one has a plus and a minus to the sound.  I found the naked Vishay to be very open and detailed, the Audio Note very sweet, Carbon was musical but kind of boring sounding but good for poor recordings, Shinkoh was emotional sounding, involving so maybe it had more "soul" and the Caddock was what I preferred in my system, kind of had it all.  With the Shinkoh you really felt like you were there when a singer really dug down deep.  You could really hear the effect of the singers lungs expanding and air rushing out so it was emotional sounding to people who heard the preamp when I switched resistors.  So IMO, more "soul".  The other resistors sounded excellent but in direct comparison were lacking in "soul".  Hope this was helpful.

Happy Listening.