Pass....Accuphase....or......

@southofdallas correct! A48 will be more stable at lower load impedance than P4600, which has higher supply voltage.

@lalitk "While the A48s is designed as a Class A amplifier under an 8-ohm resistive load” probably typo, A48 is designed as class A amp for loads = or > than 8 Ohms. for loads < 8 Ohms it is a high-bias AB class amp. 

A48 is designed as class A amp for loads = or > than 8 Ohms. for loads < 8 Ohms it is a high-bias AB class amp. 

To be clear, 'high bias' class AB amp isn't a thing. Its either class A or its class AB. In this case, class AB. Any properly designed class AB amp will not have an audible 'transition' from A to the B region.

@atmasphere then all "Class A" are  AB? Push pull Class A? Pass? What's the point with push pull Class A then? Is the ONLY real Class A a single ended amp? Why throw away the money with high bias AB? Is the heat good only for heating up the room? So many class A amps for no reason.....

@southofdallas Class A means the output device or devices never go into cutoff.

There are class A push-pull amps and class A single-ended amps, which might be tube or solid state.

Class A is used to get more linearity out of the output section of the amp. If the amp is zero feedback this is pretty important. But depending on how much feedback is used it might be a lot less important, especially in modern designs where more feedback is possible.

Topping makes a line of class B amplifiers now that have exceedingly low distortion. From a designer's point of view, you use class A to reduce distortion, so in a way we can now see that the class of operation is far less important than it used to be. There are class D amps now that easily challenge any class A amp ever made.

If the amp is to be musical, IOW easy to listen to while being neutral, what is far more important is if the amp brings home the bacon in that regard rather than its class of operation! IOW there is far too much emphasis on the class of operation; probably that was important 30-40 years ago but no longer.

"Class A means the output device or devices never go into cutoff.” - definition is correct!

push-pull A class amps have bias to cover max current for loads, supported by class a! if load is lower than nominal, one of devices indeed goes into cutoff!