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

To better assist you, can you specify which model Platinum Audio monitors you have?

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 !!!