I recently purchased a second Marantz CC4001 CD changer, after previously purchasing another unit that behaved very badly (high noise levels or would not load disk track information). The latter just got worse as time went on, so I returned it (my guess is that the laser was dying).
Before buying this new player, I compared several dedicated CD players at a small local audio-only retailer. I found the CC4001 (and its single-play sibling, the CD5001) compared very well with the NAD 542 and the NAD C525BEE single disk players. There was no problem of any kind playing some of my CDs and CD-Rs with any of these. The final choice was again based on the 5 disk changer capability of the CC4001 -- something I had gotten very spoiled with over the years with my old Sony CDP-CE545. It was interesting to me that the store owner and the two other store personnel all agreed that the Marantz players were every bit the equal of the NAD players, based on a lot more comparison time than I had. They gave the NADs a possible slight edge for circuitry, and the Marantz players an edge for overall build quality.
The new CC4001 at home has been an excellent player. I have tried out dozens of our CDs and CD-Rs, and they have all played beautifully. I have found the sound to be very smooth and clean, with some evident improvements over our (slowly dying) Sony CE545, as well as our Denon DVD/CD player in our TV room. One disk that really showed off the Marantz was the "Lord of the Dance" CD. This has a lot of high energy tracks, especially at the frequency extremes; my wife and I used it a lot to audition speakers some twelve years ago (we settled on Linn towers for our music room). The smooth decay of dance step ambient sounds in the midst of strong music is really impressive with the Marantz. Very low bass frequencies also seem better reproduced on some CDs. The only times I have heard congested sound from this player is with CDs that aren't that well recorded in the first place (typically, recorded-in excessive high frequency levels). The Marantz won't fix any built-in problems with poor CDs, but it will play high quality CDs in a way that makes us smile.
I like the small remote for this player. It isn't cluttered with nearly useless buttons and it is very easy to use. However, I wish the player had a Program button on its front panel, not just on the remote. That is a shortcoming I've found on a lot of CD players. I must give credit to Sony for its superior operating designs -- I'm going to miss that shuttle/jog dial on the front panel.
Although the CD drawer noise is comparable to the Sony's, the 5-disk tray is much quieter, faster, and more precise. One shortcoming of the Marantz player is a fairly dim display that is very hard to read from across the room. Actually, the display itself isn't bad (the Denon 390 also uses it), but the display faceplate filter attenuates the brightness.
Oh, yes, and the Marantz is one of the heaviest players I have seen. It has very good build quality, and one very massive power transformer inside.
Overall, I find the Marantz CC4001 to be an excellent dedicated CD player without even considering its relatively low price. It also has the convenience of a programmable 5-disk changer, without any associated sonic drawbacks (nor should there be). We are very, very happy with our choice.