I gave up attempts to use a PRS-350 with ADE2.0 for library books, and reverted to 1.7.2.
If the Sony was plugged in, I couldn't even read the library books on ADE on the PC.
See http://forums.adobe.com/message/4915670#4915670 if you can be bothered with full story, including various wrong assumptions I made on the way.
Version 1.7.2, it is a little difficult to find, available on Adobe site for Windows and for Mac.
http://helpx.adobe.com/digital-editions/kb/cant-install-digital-editio ns.html
The forum software is sometimes corrupting the link above. There shouldn't be a blank in 'editio ns.html'. The following redirects to the same page: http://tinyurl.com/diged172