Pass Labs:What to expect fm XA60.5 to XA100.5

Peter, is it your feeling also that the XA60s is more than enouch power for his speakers? It certainly seems that way.

A little late to the discussion here. I use XA-30.5 to drive my speakers with 91dB/w sensitivity and presents 4 Ohm load under 1KHz. I listen to music fairly loud, louder than most of my friends. Even that loud level is only around 80dB at the listening position - average. The musical peaks can reach 90dB and up. As to how the dB figures translate to the real world, at 80dB it is somewhat difficult to carry out conversation without significantly raising the voice. At 90dB you would be shouting to each other and barely hear them. Most my friends listen at 65-75dB on average. I assume that's the same for vast majority of audiophiles.

What that means is most people don't _need_ that much power in reality, unless the speakers are extremely inefficient or difficult to drive. But it's like owning a car. Most people don't need 500HP engine but we all want to.

Nelson Pass wrote about what it really means for an amp to transition from class A bias to class A/B bias. That's when the needle starts to move for Pass amps. The needle moving past the stationary position is not an indicator of the amp running out of capacity. The maximum power for XA-.5 amps are published elsewhere, and they are significantly higher than what the model number suggests. The maximum power is of course delivered in class A/B mode. Then the question is will someone be able to discern the "quality" of power delivered in class A mode vs class A/B mode of the same amp. That's a good question, but it's of no concern for me any more. The needle on the face plate jumping up and down was maybe a little bit entertaining in the beginning, for example during the canon fire of Tchaikovsky's 1812. But I came to the conclusion that my amp has plenty of power for me, and nothing good will come out with worrying about the class A vs A/B currents and needle movements. That way you tend to enjoy the music more.

Pubul57,

I think the XA60.5 should have enough power for Elmerpoh to enjoy his system. I've tried (unsuccessfully I guess) to make three points in this thread.

1) I have always benefitted from more power with my Pass amps. Enough power to drive a given speaker to certain SPL is one thing, for the speaker to sound it's best is often another. For me, the XA160.5 sounds considerably better driving my Mini II's (87dB, 4 ohm) than did my XA100.5. Elmerpoh may prefer the sound of the XA100.5 to the XA60.5 even if it seems like the added power is not needed.

2) Elmerpoh may benefit more from a Pass pre amp with his existing XA60.5 than with the XA100.5 and using his DAC directly for roughly the same money.

3) The only way to be really sure which amp he will prefer is to listen to the X350.5 and the XA100.5 in his own system if this is possible. The dealer may not allow this. It is unclear.

I have always bought the biggest Class A Pass amp I could afford at the time, and with my speakers, Eggleston and Magico, the sound has benefitted.

I bought a pair of XA160.5's based on a combination of auditioning an XA30.5, advice from Aerial about 20T's power requirements, reading about Peterayer's experience, and this commentary from an email to Pass, which might help a little. You might want to email them about your specific circumstances.

I am very happy with the XA160.5's by the way. You should know that the XA100.5's will heat your room about 50% more than the XA60.5's - I would estimate 1,400 btu/hr for the pair. The extra ~500 btu's are unlikely to matter much if you have ample air conditioning - it's like having two more people sitting in the room.

>>
>> The XA30.5 is very much a good indication of the XA line both for
>> spectral balance and detail. As you move to the larger pieces you get
>> "more" of what the XA-30.5 already is.
>>
>> The exception if there is such a thing would be the XA60.5's. They are
>> more dynamic and powerful as one would expect, but their character is
>> very slighlty warmer than the XA30.5 and XA100.5 at low to moderate
>> listening levels
>>
>> The XA100.5's are very similar in character to the XA30.5 but by virtue
>> of their ability to drive any load we can imagine, pretty much set the
>> standard for dynamic contrast and focus of image.

>> Best
>> Kent English / North American Sales
>> Pass Laboratories
>>

The comment from Pass regarding the characteristic of the XA-60.5 to be warmer than the XA-30.5 at low to moderate listening levels was not true in my system: Silverline Sonata III/Lamm L2 Reference. In fact, the XA-30.5 was warmer than the XA-60.5.