Marantz CD5003 or PS Audio Digital Link III

I would just get a DAC until the Yamaha dies. I have a Channel Islands Audio VDA 2 DAC and love it. Check out the review in Tone Audio:

http://tonepublications.com/MAGPDF/TA_017.pdf

It is a killer DAC for the money.

The PSA DL III is a great piece of gear and can vastly improve most CDPs. Since the Yamaha is reliable, the DLIII will reclock the signal, the sound is very pleasing and 3 dimensional. The only issue is the future where we may see very wide bandwidth output from players. There are some DACs that take 192k, like the Benchmark, which I have not heard but is well reviewed. I suspect there is a difference in the sound and one may be more to your liking. I can only tell you what I like and the DLIII works superbly for me.