Audio/Video not in sync

I’ll try to keep this as short as possible.  I was using a pair of powered bookshelf’s for tv audio.  Blu-ray player to tv via hdmi, optical out from tv to bookshelf’s.  The audio and video were synced perfectly.  I recently got some tower speakers and am running them with a Parasound integrated 2 channel amp.  I unplugged the optical from the bookshelf’s and ran it into the Parasound to use the tower speakers, the audio is now out of sync with the video.  How can it work fine with the powered bookshelf’s but not the Parasound?  Does the Parasound take longer to process the audio than the amp inside the bookshelf’s maybe?