QUAD style dumper with tube class A front?

OK a silly thought, but thought I'd fly it up the flagpole.
A friend suggested I build a class A tube amp for a project (I'm a hobbyist).
But class A tube doesn't intrest me, too low watts for low sensitive speakers, to much metal.
Then I thought of the QUAD current dumper amps with an accurate class A front end with the heavy lifting done by good old TO3 goodnes.
QUAD used op-amps for the class A, but I wonder if anyone has considered putting a vacuum in that spot?
I imagine all kind of difficulties here, but wondered if it's been tried before?
MFWalker