HiFi News review of Pass labs X.150.5 & X 2.5

[dejanm]

In the february issue of HiFi News there is a test of Pass Labs combo: X 2.5 and X-150.5. The comments were rather positive with the end note: 17 from 20 - which is a bit less than I expected.

For me personally two comments were especially interesting:

1.) That pre-amp X2.5 is better than Music First passive
2.) Lab report that Pass Labs X-150.5 in reallity provides 250 W at 8 ohm and 380 at 4 ohms. It would be interesting to know why this amp oficially was so conservatively noted ? If X150.5 provides 250 W/8 ohm, how much power then provides X250.5 ?

Regards
Dejan

[jacco vermeulen]

No2:

If you look over your shoulder, you'll notice that most or all US amps had much higher output power levels when tested by magazines.
I can't imagine any top level amplifier producer favors having one of its products producing 99 watts instead of the promised 100, in printing. Conservative ratings may save more than saving watts.

In an audio article, I rarely see the incoming voltage level on the primary side printed side by side with the test data.
The ones i do see, usually show a raised level alongside higher than stated output power numbers.
The old French LNRDS used to, when corrected for nominal voltage levels NP's 1st brand power amps still showed output power levels that were 15% higher.
Output power levels may easily be 30% higher during peak periods of the mains voltage, mains voltage could be at a higher than nominal level 24/7 at the location of the test facility.
The manufacturer may want his amp to deliver the promised goods also down in the Bayou, during which the light bulbs are flickering.
+50% off in the power ratings seems to remain a US power amplifier trademark.
Not just audio, engine power of US automobiles has a tradition of being rated conservatively.
Like RR. How much ? Enough.
Enough of my Mr Crab talk.

[mert]

Let's do it in that way: send them x250.5+Boulder 810 pre, they will rate as 20+ out of 20. Attention to preamplifier
remember what experts,gurus.....have told us:''always match with pre from same brand as power'' Snergy? 2 times 2 doesn't make 4 always.

[dejanm]

be careful mert - pass labs do have better models of pre-amps than mentioned x2.5. Probably 3 box pass labs pre-amp would be more logical pairing for X250.5 and also a logical competitor to your Boulder.

[mert]

maybe x-1 or 0.5 but those all from early 2000's but now we are in 2007. Boulder 810 compared to Pass 2.5 is winner in every respect. I had both together and ended with 810. But that is me. Others may choose Pass 2.5 and be happy with it. I have a tough criteria when I evaluate components. If I connect a new equipment, I first listen either there is a backround noise or any kind of irregular gain other than beryllium tweeters hisssss.
With pass 2.5 there was a noise like a ''servo regulator'' is working nearby my listening room. Imo a preamplifier has to be very quite and silent as pitch black in order to work correctly. Believe or not believe Kw500 is very succesful when it is used as a preamplifier. You know the reasons and dont need to tell you