It's like an other music EQ booster for treble and bass . Denon have 3 selections MODE 1,2, 3. I believe it a boost for music which lack or distortion in treble and bass. It works very well when listening with 2 ch music. I didn't know I always left it at HG (mode 3)on my Denon.

7.2-M80V2, QS8, VP150, M22, REAL SUB.DENON3808.EMOTIVA AMP(XPA-2 AND XPA-5)EMOTIVA erc-1 and ps3.