I was just going back through all your previous posts, and I can't be sure whether or not you have a sub!
If you don't....
Then setting your center to small won't make much of a difference(if any)
As far as the VP100 sounding small; there's a good reason......it is small. It's not designed nor intended to reproduce the lower frequencies. The low freqs are intended for a sub through whatever bass managment your receiver produces.
I won't even mention tone controls, cause I'm sure you don't have your receivers' bass turned down and the treble turned up.
If you don't currently have a sub, and funding is a problem(who hasen't a problem these days!) then there are a number of inexpensive subs available in the $80-$100USD range that would help considerably in filling in the low sounds.
