Tama naman ang setup mo, pero with your HTIB the best you can get is synthesized 5.1 from the RCA stereo line in. As with most HTIBs, walang digital or analog 5.1 input ang Pioneer mo. Hindi ka makakapag-reproduce ng true 5.1 from external sources such as your laptop.
You will need a modern AV receiver to get true 5.1. Dapat rekta ang source to receiver via HDMI, optical or coaxial.