You're not alone in this. I found the speaker bright over all as well and they were being used in a large room with plenty of hard bare surfaces . It was especially noticable with older recordings, the Beatles, rolling stones etc. With good recordings it sounded incredible. It did things with the sound stage I've never heard before or since. The clarity was next level and voices were incredibly believable. I just couldn't use them with sub par recordings.
The speaker measures with an unusually constant directivity response. That is to say it does not narrow in pattern control at the top end much at all (wide dispersion across the whole audio spectrum rather than just in the bass like most speakers)
But it's also a ribbon tweeter. The ribbon is very wide pattern, but very narrow vertically resulting in at or above average total sound power radiated into the room, but in a unusual manner.
We are certain that the ear interprets patterns from the horizontal plane differently to the vertical (were MUCH more sensitive to horrizontal pattern changes)
This means that although the total radiated energy may not be that high in the trebble, it is likely perceived the same way a flat or tilted up power response is (similar issue to the behringer 2031a)
Basically, there is nothing wrong with the speaker, It will need a 'house curve'. -tilting the EQ down from 1khz to 20khz. By how much? To taste, but start with 2db slant, but as much as 6-8db is not crazy.
this may be more true with lots of hard surfaces in the room.
