So do you have a Center channel now, or are you simulating it with your mains? With my VP150, DTS and Dolby tracks sound both good via the center channel. What receiver are you using?

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85