It seems to me that whatever software that is used to render the audio internally is the culprit. BIAB might have their own audio driver / codec to do this, or they might employ an external driver.

At any rate, through trial and error you've come to the conclusion that the rendering process is the common denominator, and by bypassing this, you have achieved a more suitable result.

BIAB & RB2025 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