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.
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.