[rmurray]

  I see that term "organic" has come up again regarding the sound of amplifiers. Can anyone verbally explain this sound ? Thanks to all if anyone knows.

[SoundGame]

Not that this is a textbook definition but "organic" would be the direct opposite of "digital".  Organic sound might describe a natural, realistic sonic signature, which comes across as smooth and fluid.  Digital sound would sound mechanical, edgy, jittery. 
 
To recreate a live performance, you want all the detail delivered in an organic manner.  Speaking to Bryston products, with the SST/2, I believe Bryston has truly achieved very organic sounding amplification.
 
Some have argued that tube sound more organic than transistors / solid-state, and there is some truth in this given the underlying technology but the application of the technology in the engineering of an amplifier can get solid state designs to sound organic.

[rmurray]

  Thanks Soundgame for that very clear explanation. I thought that may be the case but never sure. This eggs me on to getting the 4b sstsq model over my present 4b st . Much appreciated and good listening to all...............murray.

[amblin]

 For the term 'organic', i'd say it's like a nice view out of the window during sun-rise or sunset, colourful, dramatic, full of lights and shadows, . And the term 'digital' is the same scene during mid-day when the sun is directly above. Same things out there but flat and usually dazzlingly bright.

Remember that we're talking about the same scene, so they can both be 'realistic'.
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Tubes on the other hand can be even more dramatic, almost like viewing the scene during sunset through sets of colour filters, yeah, you'll be missing out on some fine details and the filters may even alter the original colours abit, but still, it's fun and there's more than enough to see.