When you say the amp inside the speaker is never put under a reviewer's microscope, that isn't entirely correct. When they are reviewing powered speakers, they are reviewing the amp when they review the amp and speaker as a whole, how the interact together and what sound they make together. It is a review of the amp contained in the speaker when the review reports how it all works together. I think that is the key rather than isolating one part of the speaker over another, it is how it integrates as a whole, whether it was successful or not.
Mike
Mike