I have an old Carver 900 ( 90 watts per channel ) and am about to purchase the 533 PT .. The question is will I fully gain the benefits of my new speakers with my current receiver ?

The speakers are the weakest link of any sound system.  Depending upon the quality of your current speakers, I'm sure you would notice a huge improvement with the PT's.

 

 

"The speakers are the weakest link of any sound system."

Next to the room's accoustics...

James

Yes, but in these cases, it's a fixed variable.