Marantz 5001 vs. NAD 515BEE Vs. Cambridge 340?

I am thinking about getting a $300. CD player.
Are any of these better in sound or build quality than the others?
Will they sound better than my 10 year old Sony changer?
Any good used players to look for at this price?

Good thread. First, I can assure you that any of the 3 above mentioned brand new CD players will sound far better than your 10 year old Sony or 10 year old anything in that price range. There has been much improvement in the electronics of CD players in the past even 5 to 6 years. Improved DAC's, power supplies, transports, etc. Now IMO, of the 3 above, I would lean towards the Marantz CD5001. Check the reviews on-line and you'll see many positive ones ( Marantz seems to have the overall balance of sound even in their budget products but the NAD will be close. Can you visit a store that sells both or better yet all 3 where you can switch between them and compare? That would be the best approach. Since Marantz and NAD compete head to head, it's probably doubtful that one store would handle both but you never know. Where are you located?
Thanks for the input.
I have only found the NAD locally.
The "Advisor" at A.A. ranked the NAD first, but you never know if that is because of the commission structure or an objective opinion.
I am in Maryland- Baltimore/DC area.
Check out for great NAD deals. Awesome dealer.
Get a used Sony 999ES dvd player. Much better than the three you mentioned and around $200.
I use a Cambridge 340C in my office system. It replaced a Cambridge D500SE after one channel started to go out after 5 years. I think the newer 340C doesn't give up anything to the older more expensive player.

I've not heard either of the other two players. I agree that probably any of them will be an improvement over your current player. However, at this price point I'm guessing that you'll be hard pressed to find any audible difference between the three. You might pick which ever one has the best warranty. The Marantz may be the better value.