I did find that one 'rudimentary' computer speaker system immediately did a total cut every time at exactly 15KHz. I doubt the issue was with the speakers themselves, but with a cut-off filter somewhere in the speaker system.

Note, this is not being critical of the test system itself by any means. That system is definitely quite useful, but the point to make is that there can be many other influences that might affect results.

Regardless, I still like the system. It has many benefits.

BIAB & RB2024 Win.(Audiophile), Sonar Platinum, Cakewalk by Bandlab, Izotope Prod.Bundle, Roland RD-1000, Synthogy Ivory, Kontakt, Focusrite 18i20, KetronSD2, NS40M Monitors, Pioneer Active Monitors, AKG K271 Studio H'phones