If you didn’t know better, you might think the phrase “class A amplifier” was a marketing ... Sure, you can build the circuits and look at everything with a meter or scope, but using Spice ...

This high-resolution audio amplifier delivers exceptional sound quality with a simple yet efficient circuit design.

It’s a conventional tube amplifier circuit in which the triode is a preamplifier for the pentode power output stage. The pentode is running in class A mode, and the high impedance of its output ...