Why can’t I tell the difference in center speakers?

Currently using a kef q350 as the center to my q750s. Decided to buy an open box q6 meta for $600 as an upgrade. I’ve listened to some movies but honestly I can’t really tell the difference. I was hoping dialogue would be night and day difference but the q350 sounds maybe 95% as good?

Are there any demos or movie scenes you would recommend for me to judge these better? I think part of it is I watch a scene and then have to get up and switch the wires then rewind it so it’s hard to have a quick comparison to “wow” me.