Quasi output stages have a delay of 10 degrees to 30 degrees in the mhz in relation to emitter followers
Output stage stability is dependent on self stability and self stability is dependent on previous stage stability. Zobel is filter and phase modification. Zobel addresses LTP stability and output stage stability. Zobel can be moved to either side of the choke to manipulate phase. A capacitor Cg from VAS output to LTP inverting input stage may introduce instability if the phase is not right, phase can be modified by a capacitor Cp to earth at VAS output and or reducing the high frequency feedback by augmenting the feedback capacitor Cg with a resistor Rg. Stability of VAS and output stage can also be facilitated using a miller capacitor Cm between base and collector of VAS. High frequency behavior of amplifier output stage is not a reliable thing. Some compensation schemes use a capacitor Ci across LTP for LTP own stability but overall amplifier behavior needs consideration. Input stage stability is provided for by a low pass filter as well as cascoding input stage. Extending high frequency behavior and fidelity of output stage using radio frequency tone control such as TMC compensation makes the output stage more prone to self oscillation, meaning it doesnt drive all sorts of speakers, that's what makes the honey badger and others quite an interesting amplifier, the other spin offs go to a three stage output to improve this high frequency performance while allowing one to use either compensation scheme. Amplifier stability is about following the phase changes at hf.