What makes the Bloom around instruments . . .

For me, "Bloom" is just lower levels of unpleasant, low level distortion, which your ear has to try to ignore so that you enjoy the music. Virtually all systems inject a decent amount of this distortion, that classic dealer showroom "in your face" hifi quality has high levels of such.

The power supplies of Class A amps have a far easier job to do, so if all else is equal there will be less of this distortion, and more "Bloom".

Frank

Elizabeth, I agree with your comments generally, except that I would say the amplifiers are not able to process the fine signal properly because of weaknesses, or problems, in the amplifier and its interaction with other components. Eliminate those weaknesses, and the amp will do its job fine.

And "general background haze" is just one of the audible indicators of, or ways of describing the unpleasant, low level distortion that seems to afflict most systems.

Frank

I always thought that "bloom" was associated with tubed amps and not digital (Spectron) or ss (Pass) amps. Its my undertanding that when tube amps distort they produce even order harmonic distortion which is percieved by most people as pleasant and musical- bloom?. When ss and I believe digital amps distort, however, they produce odd order harmonics that most people percieve as unpleasant and unmusical-grain?. I think Nelson Pass would try to reduce odd order harmonic distortion in his amp designs. But I doubt if he would, or could, introduce even order distortion to them. But I wouldn't put it Passt him(sorry but pun, unfortunately, is intended).

I would say that it has to be captured in the recording too.An amp can't make it if it isn't there,in the recording.With a good recording,then the amp and speakers and rest of the system has to be able to reproduce it.Over the decades in this hobby,my big complaint is the recordings.I listen to music that I don't really like at times,because they did such a great job of capturing it.There's nothing more disappointing to me than buying some new music I heard on the radio or somewhere,and get a bad recording.It just happened to many times.I think it would be great if these engineers that do a great job at this,would start a school for other recording engineers,so they could learn how to do a better job at mike placement,and whatever else it takes to get it done right.