Your definition of fully regulated is correct. That brings up several considerations for a particular component
1. Does it use regulated supplies? Many don't. It is unusual to have regulated supplies in the output stages of power amps and many tube circuits do not.
2. Is the design really fully regulated? Is it capable of completely rejecting any and all variations in the incoming line?
3. Is it capable of completely rejecting noise that is not 60 Hz such as RF and spikes on the line?
If the answer to all of the above is yes, then a regenerater will probably be of limited benefit. For instance, Levinson reference components already have this function built in. On the other hand, a component with little or no regulation could concievably benefit from regeneration.
1. Does it use regulated supplies? Many don't. It is unusual to have regulated supplies in the output stages of power amps and many tube circuits do not.
2. Is the design really fully regulated? Is it capable of completely rejecting any and all variations in the incoming line?
3. Is it capable of completely rejecting noise that is not 60 Hz such as RF and spikes on the line?
If the answer to all of the above is yes, then a regenerater will probably be of limited benefit. For instance, Levinson reference components already have this function built in. On the other hand, a component with little or no regulation could concievably benefit from regeneration.