As @artemus_5 stated. You need a power amplifier, such as the Adcom GFA-555, or any other power amplifier that accepts RCA style interconnect cable inputs. The combination of the Adcom pre-amp and a power amp would essentially replace the receiver, but would not have the built-in am/fm tuner.
adcom-500
I recently acquired a very nice adcom-500 tuner/ pre amp. I have never worked with pre=amps before and am curious. What device or component do I need for the adcom to drive speakers. Do I run all of my aux inputs cd - phono - tape etc.) to the back of the adcom and use the "main out norm" rca cable to an aux on my receiver. Or is there a better way? Any help would be much appreciated.