I purchased the Onkyo A 9555 to compare to the original Cambridge Audio 640A. The Onkyo won out with greater definiton, detail and better soundstage. I found my 640A to be a little thick and indistinct in the midbass. The Onkyo is smoother with less electronic glare/haze. Listening to Emmylou, Linda and Dolly in Trio II the three singers singing in harmony maintain their individual vocal qualities. This was lost through the CA 640A.