Class A, AB

"...There is no such thing as combining Class A with Class AB- such an amplifier is by definition Class AB only."

I beg to differ. I believe quite a few Plinius amps do exactly that, i.e., combine in a single amp either class A operation or class A/B. Which modality one employs/enjoys at any particular time is up to the end user via a simple toggle switch. In my mind, that is a simple yet monumentally significant design feature which even taken alone, shoots the Plinius amps way out in front of their competitors. Hard to fathom why it is not a more universally adopted design.

From a Plinius manual:

"The Plinius [model] power amplifier operates in class A and is therefore capable of generating a moderately high temperature..."

Later in the same manual referring to the toggle switch I referred to:

"...A/B position reduces the bias on the output stage to operate in class AB. This is a bias configuration used by the majority of High End amplifier designers for their products."

Sounds to me like it operates in class A as well as A/B.

And in class A mode, Plinius amps run hotter than you want to touch for very long, even while outputting no music. In class A/B, they are almost stone cold even while operating at amazing capacity.

Aldavis:
I am the opposite orientation on the A vs. AB choice -- after some intial experimentation and excitement about the sonic benefits of the class A mode, now I almost never go that route -- not so much concerned about the electrical use as the heat factor -- that is troublesome in a way that is not so easily overcome. Also I will say that in the case of Plinius at least, they are phenomenally close in AB, so I guess that makes me a "non-critical" listener for the most part.

Ngjockey:
According to the SA100 manual (page 6) "The current from the mains/line supply by the amplifier in BIAS A is now approximately 1,000 watts." So looks like the current draw actually is up by quite some margin to use it this way, also should be constant (see below).

Elizabeth:
Page 21 same manual:
"A class A circuit topology is one in which the total current the amplifier is capable of delivering, is kept flowing in the circuit regardless of the demand....
In a Class A circuit, current draw should be constant therefore there is an absence of the power supply modulation common in Class AB design amplifiers."

This under the heading of WHY IS CLASS A BETTER? So again, it sounds to me like these amps are switchable from Class A to AB.

Oh yes, there is little doubt that when it comes to audio review, people are not hearing the same thing. That is why the only real way to determine if a given component is for you, is to buy and listen in your own environment -- enter Audiogon.

Interestingly, I try to stay away from really narrowing down what something sounds like because of this factor, and whenever I break from that, inevitably it has a predictable result. Had a buyer recently work really diligently trying to get me to characterize the sound of a piece I was selling. I explained my position, but gave at least that it was one of the more "dynamic" pieces I had heard. He bought it, and was happy, but one of his first comments: "Does not strike me as particularly dynamic." All I could say is "there you go..."

Oh, not at all...to tell the truth, I was not even referring to your use of the term "non-critical" -- the Plinius manual also refers to AB listening in those same terms. I was just amusing myself by restating that characterization because it strikes me as funny that my listening habits might EVER be considered "non-critical" -- I ALWAYS, even on a moment by moment basis, find something to criticize in whatever sound I have going (but nothing that ever really prompts me to want to use the Class A switch, I must say...)