Pass Labs Xa60.8 Class A or should it be called class A/B?

All ‘class A’ power amps transition to A/B at high levels!

Nothing sinister going on here.

Thanks everyone that answered my questions.  I didn't mean this as a bash against Pass, rather I was just curious as to how this all works. As I said in my original question, I'm probably going to purchase the XA60.8 so no worries at all about them doing something sinister.  

XA60 is a great amp. 

All ‘class A’ power amps transition to A/B at high levels!

Sorry not true.  The distinguishing characteristic of a true class A amplifier is the quiescent current is at maximum with 0V output and to produce output away from zero the opposite leg's current is reduced.

An amp that transitions has some quiescent current far below maximum which then is INCREASED above a certain threshold during which the opposite leg eventually shuts off.

These are the two required characteristics for a true class A:

• Maximum current and power goes through the transistors at 0V
• Neither transistor side ever fully shuts off.
  

There are a number of Class A amps which fulfill this requirement.

Of course this makes true class A amps monsters in terms of electricity consumed and heat output.

I also want to point out that it seems Luxman also does a similar thing with the L 590, but I'm not entirely sure.  They sell it as a 30WPC integrated but measurements indicate it can do much more around 100WPC.  Perhaps it is also a "high bias" class A/B?  It is also possible it is a true class A amp but can't handle the required preconditioning load so they instead underrate it.

Let's think about it the other way round.

How many amps described as class A/B offer 122w of class A power?