If the DutchDutch "sounds excellent" despite these THD numbers, how relevant is the general THD/SINAD focus of this forum? Note that this isn't a comment on the performance of the Dutch specifically, but the general focus on THD in relation to the result of this test.
Imo, not super relevant for speakers. There have been a few cases where I think it has been clearly audible(ex: 308p), but for the most part they're all generally in the range of completely inaudible to slightly audible with sine tones. Even when it is audible, like with the 308p, it's still doesn't matter all that much compared to other performance metrics.
For electronics, I personally see it as irrelevant(though there's always exceptions), which is why I never read the electronic reviews. People like having a number to compare though, even if that number makes no significant audible difference.
A $12,000 set of speakers shouldn't need such a discussion.
Given that this is likely the best $12,000 speaker (this or Kii3) in the world, and definitely the best measurements we've ever seen here, I don't really understand this. No speaker does everything perfect, even at this price. The 8C does the things that matter a lot(extension, directivity), better than anything else we've seen, while doing the things that don't matter(distortion), or matter very little, mediocre.
@q3cpma showed that the 8C's 100Hz H5 distortion is above the audible threshold, but that's for sine waves, not music.
It seems that a conscious decision was made to sacrifice distortion performance to gain directivity performance and extension, as
@Kvalsvoll explained. A good trade, imo, considering just how much more important those latter two performance metrics are. For the distortion difference, we're likely talking "ever so slightly audible to trained listeners with less than 3 second switch time on certain segments of certain songs". For the directivity and extension difference, were talking "easily audible to untrained listeners with 3 month switch time on almost any piece of music". A very good trade indeed.
So, show me a speaker that has better distortion than this speaker(@ $12,000), and I'll show you a speaker that has less extension, worse directivity, or both. A speaker with better distortion performance, but worse extension or directivity, is a lesser speaker, which is why your statement confuses me. Now that the standard has been set, it would make more sense to go to the Revel F28Be review and say "Why does it only control directivity down to 500Hz? why is the extension so poor? A $16,000 speaker shouldn't need such questions"