It is not about SPL level.
The real problem is dynamic congestion & lack of nuance.
I'll have to disagree. Desired SPL levels are a very basic factor in amp/speaker compatibility. It's rather like claiming horsepower or torque are meaningless measures for a car engine. Just because there is more than one factor to consider doesn't render a fundamental measure irrelevant.
Dynamic congestion certainly becomes an issue if the amp is being called to deliver power it doesn't have on the transients. That is inevitably tied back in one form or another to speaker efficiency versus available amp power. Far too many people are perfectly satisfied with SET amps to automatically discount their suitability in this situation without further examination.
Similarly, far too many people overstate the dynamic range of recordings. When you're playing back a loud section of a piece of music, with rare exception for a few specialty recordings, there just isn't another 15 or 20 dB of dynamic range hidden in the background. That is why it becomes important to have an accurate reference point for the average desired volume.
I've seen some people describe an average level 75 dB as "loud" while I've seen others listen at 95 dB and still want to crank it further. So when the original poster uses the term "moderately loud", I have no idea what that really means in his case.
But, if one can take the phrase "absolutely splendid" at face value, it certainly seems he is well satisfied with the amp in combo with his current speakers. If he's running his current amp close to the edge, he might well be disappointed with the different speakers. Or, if his amp is still coasting in the current setup, he might be very happy with the speaker change.
