Pass Labs A/B amps vs Class A amp and Actual Power

Stickman, are you sure that the XA 100.5 maintains Class A bias (or something to that effect, as there has been discussion here on the technical classification as to whether Class A/AB and Class AB amps technically deliver any Class A bias(?))or is the Class A Bias reduced and the Class AB increased as it doubles down?

Stickman, many if not most amps that are touted as doubling down Class A amps actually halve their Class A out-put as they do so. Including Nelson Pass' previous Threshold designs:
http://www.stereophile.com/solidpoweramps/1290thresh/index1.html

All the more reason to make sure your buying what your expecting. Mind you, the same might be true re: doubling down power/halving Class A bias for the amount of Class A bias in the Class A/AB amps.

Rtn1, I was merely asking a question, and based upon Nelson Pass's (albeit different) previous Class A designs, the question was appropriate. The Pass web site does list the XA 100.5 as "Leaves Class A at pk Watts: 200". I'm assuming pk means peak. Does that mean sustained power or short term peak headroom power and into what impedance load? It doesn't appear to be all that clear to me.

Rtn1, I don't have access to those measurements. Am I correct in assuming that those measurements are suggesting 150 Watts per channel into 8 Ohms and 200 watts per channel into 4 Ohms? Do those measurements specify that the first 60 Watts into 4 Ohms are in Class A, or are you assuming that they are?
Again, though of a different design, Nelson Pass's Class A/AB Threshold amps provided the first 20% of out-put into 8 Ohms in Class A and the balance in Class AB, into 4 Ohms the Class A output dropped to 10% and the Class AB doubled it's output. In his Class A Threshold amps the provided 100% of their rated output in Class A into 8 Ohms, into 4 Ohms they provided 50% of their output in Class A as the balance of power output doubled into Class AB.

Brian, good question. There have been discussions here as to whether there is in fact such a thing as Class A/AB or for that matter even Class AB. Some here claim that there is either only Class A or Class B, but not combinations there in. It might be just that some amplifiers have part of their out-put having attributes of Class A. I don't have any where near the technical expertise to determine what is what. I will say that more often than not, those amplifiers that claim to have more Class A output, do sound better to me.