Hi i have platinum audio bookshelf monitors that do not sound right...

Wires (Cardas) are correct.
Model name "SOLO"

What don’t you like with your current setup?   How large is your room?  What do you listen to?  How loud? 

They might also need work on their crossover. I only say that because they're getting a little old now, and it's hard to imagine that a 7100 isn't enough to drive those speakers. 

The room is rather small, (14' X 12') 12 foot ceilings, listen to all types of music (not tooo much rap please), at moderate levels. I do however have to turn the volume up over 3/4 to get a punch !!!

Having to turn it 3/4 of the way is not an issue, it just means there is not as much gain than some other combos (your amp has adjustable gain).  Are the power guard lights on the amplifier coming on, which would signify clipping?   That amp should have enough power to cause the woofers in those speakers to bottom.   

If I were looking at an upgrade, I would be looking at the preamp, but from what you are saying, there is no issue, and no reason to upgrade unless you want to.