Audiofly AF78 Dual Driver In-Ear Sound Isolating Earphones in Marque Black. A duet of technologies Audiofly s dual driver AF78 combines a professional grade balanced armature driver with a 9mm dynamic driver. This hybrid configuration draws on the strengths of both driver types to produce truly sophisticated sound across the entire frequency spectrum. A duet of technologies: dynamic driver and balanced armature driver. Audiofly s AF78 is your ticket to truly sophisticated sound.