A few years back I was looking for a CD player with a headphone out. I was eyeing the Marantz CD 6002. I auditioned the Marantz CD5001, CD6002, SA7001 and a Denon that I don't remember and cost more than all the Marantz. I went home with the Marantz SA7001, I wasn't prepared to spent that much but the improvement over CD6002 was IMO substantial even with red book CD.
Subjectively speaking, all the Marantz has a lively sound signature to them, the Denon sounds warmer and mellower in relative to the Marantz. The Denon was highly recommended to me by the sale rep but I wasn't impressed by it, may be not my cup of tea. All those heard with an AKG K501 directly plugged into them.