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

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."

Eril, you live in a beautiful country! The closet I have gotten to New Zealand was a trip I did to Tasmania two years ago. If the MAN himself, Mr. Nelson, says that's the major differences between his amps, who am I to argue. I would just add that as you go up in the X-5. series you get more and more of that special "organic" sense because of the higher single-ended class A biasing. I wrote a review here on the Gon about my experience which lead to me replacing an Edge-NL10 with the PassX-350.5 in my system. You might want to take a look at it. This "organic" sense is subtle in the Pass amps but after you hear it, its hard not to want it in your system. I think its time for you to have a home audtion and let your ear's decide what you like. Please share what your experience/decision is after you listen with us. Thanks.

Eril, in my last reponse I forgot to address your question concerning Pre-amps that are good matchs with the X.5-amps. I'm not an individual who is to enamored with tube Pre-amps, but let me share what I have heard with my own ears regarding the matching with the 350.5 in my own system. I replaced my highly regarded ML-32reference pre-amp with a Placette dual mono active line stage. It blew away the 32 on every factor(dynamics,transparency,soundstage,timbres,extenstion of bass,etc.). Not inexpensive, but a bargain at 4,500.00 dollars. You buy it factory direct with a full month audtion period with a full money back guarantee. Mr. Placette,Guy Hammel, is a great guy and a real gentleman along with being a genius regarding his Pre-amps. The other Pre-amp which sounds gorgeous with the X-.5 series is the highly rated, rightly so, Lamm reference pre-amp which is a hybrid tube/ss two box piece. However, it sales for over 12,000.00 dollars. The combination of the Placette active linestage and the Pass LabsX-350.5 is just exceptional in my system and I'm totally happy with this duo. Finally, someone I know has just changed his Pre-amp to the Herron tube linestage with his 250.5 and loves this combination. All three Pre-amps would really sing with any of the X-.5 amps along with many other brands/types of other amps. Hope this helps.

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."