[Vorbis] Updating an existing file encoding

[dpk]

I'm not a list subscriber, so please be sure to include my address 
explicitly in replies.  I ask the list as I haven't found a solution 
elsewhere.

I've been using (and quite happily) Ogg Vorbis for awhile now.  I 
recently purchased an iRiver player that supports Ogg; however, I 
noticed it won't play certain files/albums.  I believe it is because I 
encoded files prior to Vorbis version 1.0, specifically 1.0 rc3.  Is it 
possible to alter the existing files to be compatible with new standards 
without loosing quality?  I was hoping there was an easier way than 
digging out all my albums and re-encoding.

Thanks,
Dennis