Class A into Class AB

this may help

https://www.firstwatt.com/pdf/art_leaving_class_a_2019_redux.pdf

i am not sure what downsides are introduced if the biasing current is increased in an amp such the bryston... (other than the obvious ones like more heat generated and power consumption)... there must be a point at which something in the circuit can’t handle it, or further increasing the bias yields no more sonic benefit, or something else bad happens.

with vacuum tubes there is clearlt a range where the power tubes are comfortable and producing good sound but not running too hot and burning themselves out needlessly fast (analogy would be a car engine with idle point set ideally, versus idling too low or way too high)

perhaps ralph can chime in

now that we are all confused and mystified, to add further complexity to matters, nelson in his well and densely written owners manual material for my pass int 150 says - (i am paraphrasing) - this balanced topology amp produces 150 wpc class ab into 8 ohm, but the first 15 watts are run in class a, and the first 2-3 watts are single ended (as opposed to push pull) class a

does that make sense? it must cuz nelson usualluy doesn’t fool around and b-s much, but i am wondering how this works

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separately, it is certainly my experience that within the power envelope of the class a amp, they sound purer, sweeter than their class ab counterparts - evidenced by my own comparisons between the belles sa30 vs sa150, schiit aegir vs vidar...