Considering whatever has been said,
it is always a good thing to see 45w @ 8ohms with less distorsion than usual. Having 4500watts with crazy THD (like Devialet uses to deliver in class D, for example) makes me much more anxious... Far more dangerous electrically speaking, and much more useless, fidelity speaking to what the impulse become, passing through 4500watts of highly distorted and unstable power.
So you could sometimes satisfy with less watts and more stability, less distorsion, more fidelity than high power massively distorted.
Our amplifiers are not just about power. Considering how each watt is handeled by the amplifier gives you more fidelity, more accuracy, less need of equalisation, more neutrality and is always more easy to listen to than loads of crappy watts.
You could find some 45w amplifiers highly distorted that really don't please your ears and you could find 45w of non distorted watts that give you a more "full bodied" and "natural" type of feeling than some higher powered amplifiers in low sensitivity speakers. And you'll say that it sounds more powerfull than you thought, but no it just uses each watts in a cleaner way, it is more efficient per watt used.
So yes a 88db or less sensitive speakers could always claim for more power, but when 45w are well done you could drive quite a lot of loads with
great and good or just fine surprises to your audition.
I think all that amir is testing on this forum tends to show and explain exactly that it is not only about sinad, power stability, frequency, all taken appart, for an audio component to be good.
But the sum of all these measures taken in order in one audio component to know that, if it checks all the boxes right, it might be a component to consider as a "good one" its efficiency in all parameters together is far more important to consider than just one aspect of its technical sides.
Of course when you see 100watts or more well managed like Purifi amplifiers, McIntosch or Benchmark, it is quite phenomenal to consider for your experience, because it assures you to be able to drive any load without adding distorsion, comparing to what we find on the market nowadays. Thus these amplifiers remain absolute great powerhorses for hifi, they ensure that you won't need to change your amplifier if you buy less sensitive speakers.
But anyway, at 40watts, this amplifier gives really gooood performances and not long ago everybody was fine with 30 to 70 watts in tube amplifiers with looooooooads of distrosion...