The VP180 has fundamental design problems. It might have a dynamic range advantage, but it will definitely not have clearer vocals at any loudness level. The Prime center should yield clear vocals without needing to be loud. This makes me think you might have a setup issue. Make sure that the center speaker is not in a congested area. If you are running the system with some kind of automated EQ calibration, turn it off. Make sure the center speaker is aimed right at the listening position. Also make sure you don't have big reflective surfaces along the line of sight of the center, such as a big coffee table. Make sure the bass isn't too hot; loud bass can mask midrange sound, and that can really hurt dialogue intelligibility.