Yes. The hypothesis frequently posited is that the Stax-branded amplifiers (besides the 717, 727, and maybe the 323S [?]) tend to be less consistent performers in driving a "challenging" load (the SR-007Mk1 is frequently the load brought into example).
If this is true and the SR-009 was evaluated in development with a Stax amplifier that couldn't handle the load, it could have some interesting implications for the performance of the unit on amplifiers that can vis-a-vis the performance intentions of the engineers behind it...
It's a matter of word selection and personal meaning attributed to those words.
I never thought the SR-009 and KGSSHV (or T2DIY) combo was "bright" with the sources and recodings I used. However, I can certainly see people finding the SR-009/KGSSHV overly analytical, too etched, or too edgy (which is separate from brightness) depending upon source and recordings used. Combined with the fact that the SR-009 doesn't have the HD800's broad mid/high bass bump, all these factors could certainly contribute to people finding the KGSSHV setup "bright". As a saide note, the combo that I found painfully etched and strident was the SR-009 + Headamp BHSE (not to be confused with n3rdlings BH) + Oppo (SABRE) regardless of recording. (the BHSE has always seemed "brighter" to the KGSS/HV builds I have heard)
That's a fair assessment. Translating perceived perceptions into relatable auditory lexicon will continue to be a pain point. Audio linguistics can be challenging when one man's musical is another man's mellow, et al.