I just looked through manuals for YSP2500 and Q acoustics soundbars.
Neither seems to have a mechanism to control how 5.1 sound will be mixed down, so you can manually control the relative level of the centre vocal speaker - is that correct ? you just have to go with their pre-programmed modes.
(I want to get one of these for a parent, harder of hearing, and the ability to control the mix, or maybe have a graphic equalizer of some sort was on my list of needs.)
Not entirely sure if I get what you mean but there's a clear voice setting on the 2500 and each individual channel can be adjusted up or down as well, it has several equaliser setting for films, music and games