You also need to make sure that the front edge of the speaker is hanging out a bit over the edge of the shelf/TV. The sound can be quite boxy and hard if you are getting reflections off a flat surface right in front of the speaker.

I'm fairly sure (but not 100% sure) this applies to any center channel speaker, not just the VPxxx series.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8