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

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."

Eril, If you live in NZ, I would give Paul a call at PQ imports and see if you can have a listen to a VTL pre-amp if you are not against tube pre's.

Pass Labs are wonderful designed amplifiers, Pass Labs offer a substantial range of amplifiers to match most loudspeakers manufactured today.
If you are looking for a Pass Labs amplifier in New Zealand please contact Parmenter Sound.
www.parmentersound.com
Thanks Jason Parmenter.