Threshold/ What is the Stasis topolgy?

Unsound-I copied word for word the explanation for the Stasis topology from my manual.
You are correct about a longer class A operation.
You dont think 45 amperes is high enough for the S/500? :>)
Also,Im 90% sure they double down,but not 100%

David, I didn't know that the S/500 was capable of 45 ampres. Is that steady or peak? While that certainly seems adequate, it's not tremendous for a 250 watt per channel amp. To those in the know, such as yourself, it sure does seem to do the job.

From the Threshold Service Manual. 16 Amps continous with 40 amps peak. Bout as bullet proof as it gets. Produced from 1980 to 1984. 1984 was the Series II propagation. Have never seen one of these fried. However this amp is very unforgiving if the rest of the system is not up to the task. Don't skimp on the preamp or rest of the system, and lastly, tube preamps do not work well with this amp as the input impedance is 75,000 ohms. Needs to be powered 24/7 for best sonic signature and thermal stability.

Definition of Optical Bias on Threshold Amps is below.

In the case of my patent #4,752,745, an optocoupler is used
to transmit the value of the bias current to an earlier stage
which contains the bias circuit. It works very conveniently
to keep the bias at a constant value while isolating the
front end VAS from the output.

This is from Nelson Pass.

Thank you Ferrari. Forgive my ignorance, but, what is an optocoupler and what is VAS?