I must agree with Thedautch. Source is extremely important for a quality sound. You could have megabucks invested in amplification and speakers with a mediocre CD player, and all you would get is the ultimate ability to hear how mediocre the CD player really was. Within their limitations, speakers can only reproduce what is fed into them. I proved this to myself years ago when I had about $15,000 in electronics driving a pair of $300 speakers temporarily. It actually sounded surprisingly good. Now I do agree, a system can only be as good as the weakest link, but a poor quality source cannot be improved by any amp or speaker.
The analog audio out from the Pioneer is probably a very inexpensive circuit, since the player is designed for video. I would try a digital audio out to the B&K to use its DAC and analog circuits. If you do notice an improvement, then an outboard DAC would be better still, or just add a very nice CD player.