Drew, I have a much lower-end Yamaha than yours, paired with the Epic 80-600. To my ears, the VP150 stands up quite well to my mains. And the 80's are killer.
If you could please tell us more about what you are disappointed with. Is it the actual tone, volume, or impact of the speaker? You were a little vague.
As the others have asked, what are your settings? You don't seem to acknowledge them when they ask you this. I can't stess enough how IMPORTANT this is. Also, make sure the speaker is protruding PAST the front of the TV.
Did you use the YPAO auto adjustment? It is notoriously bad, and may REALLY throw things off. Start by shutting it off and set the system up manually. Do you have an SPL meter? If not, get one.
Apart from the standard x-over and small/large settings, you can also adjust dynamic range (low/normal/max), centre channel "width", centre channel "raise", and certain EQ frequencies.
Again, you need to address these issues FIRST. Adding more amplification, or a second (or different) centre won't solve your problem if the settings are messed up. After all this, if you still don't like the sound of the 150, by all means buy something else. You won't have any trouble selling it.
