Cable upgrade

Center speaker is only 2 months old and has been rated to be quite a good center speaker.
I am using the Bryston bbs2 for my contour 5.4 fronts and am using the Arcam avr 600 to drive my rears and center.
I'm not to sure where I'm going wrong?
If it's the Arcams preamplifier section then what would you recommend?
I have tried different cables such as Tara labs vector 2 and chord signature and did hear a difference but these were only minor differences.

Here you go:
http://signalcable.com/silverresolutionspeaker.html

I just tried some nordost Valhalla cables for front three speakers and it made a huge difference to the sound.
The clear opened sound that I was looking for these cables gave me.

You could also adjust the level of your center up if
you havn't tried this already.

I had tried to up the level of the center speaker but found that these cables made the biggest difference.
The sound for movies is so opened I can understand everything that is going on.