"Mini" to Optical for Airport Express

Okay...so we have established that such an animal exists. Now the question is, sonically, am I better off using the analog out of the AE and the analog in of my preamp OR the digital out of the AE and the digital in of my preamp?

Thanks,

Lawrence.

Once again, thanks to all.

The pre-amp is a Rotel 1066. However, I am considering an external DAC. The rest of the system is a Rotel 1075 and Paradigm Studio 60 V.3s (for two-channel listening, although these components make up part of a home theatre system as well).