Yes, the Parasound has plenty of power for the S4. I had those speakers at one time powered by a 60w integrated, and they sounded fantastic. When mated to the with the Parasound A23, they really came alive.
Not to offend, but I found the S2 to be the better speaker. It imaged better than the S4, and since you will have a nice sub to handle the LFE, you are waisting money on the S4's IMO.