Solid state AB amp?

It depends on your amplifier,  most A/B amps will play 1 to 5 watts before switching.  So,  it is likely that you will be using class A for 1 watt.  

In that regard, its probably only running off of the driver transistors rather than the output devices.

Two speakers increase of sound pressure by 3 dB, doubling listening distance from a speaker reduce sound pressure by 6 dB. Doubling the amp power output wattage increase sound pressure 3 dB.
Its depends on how far is your listening distance and how much class a power your amp has before it switch to class b.

My amplifier is the Passion 650.  The reason for my original question was how sweet it sounds at such a nice listening volume for a jazz trio. Thought that class A could be running alone
atmasphere would you explain what that means?

I found one user review which claimed it uses what they call an "alpha Class A" circuit, but I couldn't find much more about it.

Is that the one they use in submarines? 

YBA calls "class Alpha," which means that the driver stage is class-A but the output stage is class-A/B
Read more at https://www.stereophile.com/solidpoweramps/831/index.html#84RYQxlcHp4utR9l.99

Thought that class A could be running alone
atmasphere would you explain what that means?

class A means that the output transistors never go into cutoff. In your case the output transistors cutoff at slight more than half of the output waveform.  This is to prevent any distortion at the critical point where the signal goes from positive to negative and vice versa. Class A makes significant heat since the transistors are on all the time; class AB makes a lot less heat and also more power.

The following excellent article by Nelson Pass may be of interest:

https://www.passlabs.com/press/leaving-class

Regards,

-- Al

Thanks guys

On the courious side...What type of amp do you have?

YBA Passion a650

Almarg; great link. Thanks again 

Then you read what Sanders has to say and you really start scratching your head.
http://sanderssoundsystems.com/technical-white-papers/53-esl-amp-bias-white-paper

It all comes down to what you like the sound of best. 95% of the population couldn't tell the difference between a Pass amp and a Sanders amp. Only crazy sick bastards like us care. 

I don’t think so. Say, the bias is equal to 70mA. This current must be the amplitude current of the speaker. Say, you have 8Ohm speakers. The highest power P = I * I * R / 2 = 0.02W. If your speaker has 101dB/W/m you will get 84dB maximum. Class AB amplifiers have higher distortion on high level (it is obvious) and on low level (because of "step" on their characteristic). Just if you have the amplifier with bias about 0.5A or more it can work. But the heat dissipation rises very fast in this situation.
Try my page in linkedin.com (Vladimir Benkhan). I describe there how to improve quality of regular amplifiers and there is a scheme of simple class A amplifier there.

Vladimir you lost me after "I don't think so."

A or AB my amp,  along with my SET  Preamp; KIND OF BLUE and of that ilk does it for me. 
thanks