For what it's worth, in all but a very few cases, when high-end audio amplifiers label themselves pentode, they're actually ultralinear in operation.
Ultralinear is a combination / compromise between triode and pentode. You could argue it's the best of both worlds. Or, you might argue it's the worst of both worlds.
Ultralinear is a combination / compromise between triode and pentode. You could argue it's the best of both worlds. Or, you might argue it's the worst of both worlds.