Is "BLOOM" a sustainy, harmonicy, type of thing?

[Tonician]

Bloom, as discussed here, in my understanding, subject to change, is the reaction of the amp to an input of amplitude great enough to cause clipping, which is a momentary near short of the tube, which pulls down the power supply voltage. This changes the slope of the output relative to the input. It is heard as a slower rise in output, then as the input signal decreases, the clipping decreases and we hear a leveling out of the volume, which is heard as the note being sustained. It is more pronounced in amps with tube rectifiers due to their current related voltage drop, and with chokes that filter, and drop fairly large voltage at higher than rated current, or the cheaper series resistor.
What I don’t understand, and sincerely would love to understand, is how this can happen at lower volumes where clipping and distortion are not prevalent. Is it from the preamp? Is it a different function of at lower volumes?
Clarification and education appreciated. Sincerely,
Tonician

[phsyconoodler]

I have never heard any amp other than very select Dumbles do it, or at least anywhere near the extent that 183 does it.

I play with a guy who has a Boogie MkIV and he gets that amp to bloom like crazy with his G&L tele with humbuckers.But that's pretty much the only Dumblesque sound he can get and he needs distortion to get it.He sounds very much like Robben Ford.
I can't play like he can and my amps will bloom rather easily even with this old blues player playing them.
The bloom comes easily when you use a combination pick and finger style.
Very vowel-like.