Meridian CD Players

I am looking at buying a new (well used) cd player. It is between the meridian 506 and 508 series... (probably 20, not 24). I currently have a mcintosh mc-275 amp, c-22 pre-amp set up. I am wondering, what are the differences between the two products that justify the cost difference? Have any of you guys put them head to head? All I know is that the 508 comes with balanced outputs, which i dont need as my preamp doesnt have balanced inputs. What can you guys say about the difference in sound quality? Any information would really help....Thanx!