The Stereophile test CDs also have good recordings of someone walking around the soundstage and stating his position. If your system isn't able to properly place him, something in your setup is off. Yes, more recordings than not will place vocals between or behind the line between the speakers, so that will be most commonly heard across recordings, but it shouldn't always be so. Great systems will place the vocals forward if that's what's on the recording. Cheers,
Spencer