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

Eril, this can be a little confusing unless we define which generation of X-amps we are talking about. In the original X series the X-150 became the X-150.5 when Pass decided to add the blue meter to the front of the amp, which the X-150 lacked. Otherwise, the amp was exactly the same. I'm assuming your question is regarding the new generation of X-.5 series, which is a major revamp of all the X-series amps. All the new x-.5 amps sound terrific in their price range. What you get as you go up in the series is not just more power, but higher initial single-ended class A biasing for certain amount of watts. This is followed by a number of regular class A watts untill the amps go over to class A/B. Because of this the 250.5 will give much more of the taste of the Pass Labs X/A series amps. The dynamics, slam, transparency of the old X-series with the warmth of timbres and organic/liquidity often heard in tube amps. I have the 350.5 in my system and enjoy its virtues on a daily basis. The 250.5 will give much more of the above stated sonics then the 150.5, even though the 150.5 is terrific at its $ point the 250.5 is just that much better. Hope this helps.

Calanctus, I have no information that would put in doubt what you stated on the Pass Labs website. I remember a long time ago that I talked to someone in Pass's office who said their was no sonic difference between the 150 without the meter compared to the 150.5 with the meter. The new 150.5, along with the whole new X-.5 series, is a different matter entirely. Remember, Eril, its not just class A biasing in the new series, like your Cairn amp, but single-ended class A biasing for certain amount of watts before going into regular class A. This gives some of the sonic virtues normally associated with tube SET amps. The 250.5 lives in a different sonic world than your Cairn Intergrated amp, which is great for its cost, but is not is not really competitive with the 250.5. But remember your comparing amps that are a least $4000.00 different in their prices. In this case more $ really brings a much higher level of performance, often more $ doesnot = better.

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.