The ref3 and this Meta loudspeaker seems to be slightly different at on axis response , the ref3 is brighter voiced.
I do see that the measured on axis responce is slightly flatter for this speaker vs the R3.
It would be interesting to A/B/Q them.
Perceived brightness is dependent on so many factors. Think about High Passing a favorite pair of speakers at 120hrz, then add the bass back, then add a robust sub.
Now a dynamic speaker on an intense passage vs a less dynamic one. A speaker with slightly elevated treble on a sweep, might sound less bright due to presenting less dynamic SPL.
Dispersion is also huge factor for me in perceived brightness. Low distortion is as well.
One thing we hardly ever see IMD testing of tweeters. Some tweets sing at high SPL in complex areas and others are really stressed even if HD on sweep is fine.
Interesting for me at least, my pair of R3's did not really measure with that slightly elevated treble when simultaneously measured with several other speakers.
In practice, in my case the R3's never once sounded siblant, brash, harsh, shrill or anything along that line(unless it was due to poor recordings) and I listen to some crazy stuff sometimes.
Who knows.
That is the subjective part.
Over-all both speakers measure so well.
Shame I didn't dig the R3's. Did a lot of testing/listening, appreciate the speaker but it just wasn't quite there for me.
The Reference 1's are to $ for me to try currently. Maybe someday.