What Difference between Pass X150.5 and X250.5?

Thanks Teajay.
I am currently using a Cairn Integrated Amp (first 10 watts in class A) with my Jean-Marie Reynaud Evolution 3 speakers. 88db sensitivity - easy to drive but do better with high current and high damping factor.
The speakers are well banced but a tad soft/warm.
I like the Class A sound better than any AB or valve sound I have yet heard and I thought the new Pass X-5 series was a good potential match.

Thanks again Teajay.

Yeah I sort of appreciate the difference in the Class A stuff. I live in New Zealand. We get stuff all here so I import. The Cairn Fog 2 CDP and 4808A were my first venture into good audio. Loved it so now moving up. Started with Combak Reimyo CDP-777 - which is outa-this-world-wonderful - I don't want valves in a power amp and can't afford XA series. But I am also wanting a great valve pre-amp . Any thoughts on what works well with Pass X -5 series?

Two different Pass dealers say internals are the same between X150.5 and X250.5 - power and Class A bias are only real diffs - X150.5 goes over at 15 watts - X250.5 at 25 watts.
Nelson Pass himself says "authority and control are only big difference. The other audible differences are subtle."

Info just in from Pass.
Per channel continuous:
X150.5 10 watts
X250.5 40 watts
X350.5 50 watts
With higher instantaneous peaks.

teajay - thanks for your thoughts. Auditions are impossible for Pass, Herron and Placette here in N.Z. I have heard several passives and they don't "do it" for me.
The Pass pre-amps are considered a little on the dry side by the Australian importer - I will buy from him, great dealer.
So I will continue my research on suitable pre-amps.

Latest in from Nelson Pass:
"The X250.5 and 150.5 differ in power supplies, output stage size, and bias. In these amplifiers
the first few watts are single-end Class A, and they leave push pull Class A at something like
20 watts and 40 watts peak respectively."