Has anyone used the Yaqin tube buffer? I'm currently using a Marantz cd5001 cd player with a NAD C720BEE receiver connected to a pair of Revel Concerta M12's. I'm pretty happy with the sound, but a touch of warmth would be nice. On the one hand, I figure that for the money, why not try it, but I'm also thinking that if I'm happy with the sound, don't mess with it. Anyone used this buffer with NAD?