Thanks Guys....interesting and useful ...now for a follow-on question. I have all my music on my computer in iTunes in WAV format (don't how that happened-not sure unless I changed it from AAC in ignorance) is this better than Apple Lossless or *.ape or of a lower quality?
Assuming that .ape or ALAC is better, do I lose anything when i convert using MC?
Or should I re-import my music in ALAC or .ape(and its a lot!)? I can handle the answer 
, just want to know what gives the ultimate best audiophile quality.
Thanks again for help so far
iTunes does not support secure ripping, and has error correction disabled by default (what a stupid default setting!)
JRiver Media Center can use secure ripping, however it does not compare the final ripped results against the AccurateRip database.
I prefer to rip in dBpoweramp (which is a paid application) because it supports secure ripping and does a number of other checks to guarantee the file is a 100% copy. (EAC is free and can do the same, but it is a pain to set up)
So I would switch over to at least ripping in Media Center rather than iTunes in the future. You may or may not want to re-rip your discs. It shouldn't be necessary, but there may be pops & clicks if the disc wasn't read perfectly.
If you have a large library, and still have a copy of the discs, it's probably not worth the hassle of re-ripping everything again. If an album plays and does exhibit these problems,
then you might want to re-rip it.
WAV is an uncompressed format and sounds identical to a Lossless format, the difference is that a Lossless format will compress the files about 50% on average. This saves you disk space, but keeps audio quality the same.
Unfortunately WAV has limited support for metadata (information like track name, number, album etc.) and iTunes does not support writing metadata into WAV files at all, and only keeps it inside its database.
Because of this, I would recommend converting from WAV to Apple Lossless before you import the files into Media Center because then iTunes will write all the metadata into the file itself so that Media Center can read it.
If you don't want to use Apple Lossless in future, Media Center can quickly convert the files to any other format you want, but you need to get them into a format that supports metadata before you import them, and that means Apple Lossless or AIFF in iTunes. AIFF is also an uncompressed format like WAV, but iTunes supports writing metadata with AIFF files.
To do this in iTunes, you need to set the import settings to Apple Lossless Encoder, which should then give you the "Create Apple Lossless Version" option on the right-click menu inside iTunes. Unfortunately iTunes creates duplicate files rather than replacing the files when converting formats.
Next what you want to do is create two smart playlists. Firstly, one that will only display uncompressed files:
And one that will display converted Apple Lossless files:
You may also want to create a "Lossy" playlist for any AAC/MP3 files with Kind
is not WAV audio file, AIFF audio file, or Apple Lossless audio file, to display the other files in your library. (that you should not convert)
Now you can select all the uncompressed audio files in your library (hit Ctrl + A in the "Uncompressed" smart playlist) right click them, and convert them all to Apple lossless. Once this is done (it may take a while) you can then import these files into Media Center.
To import them into Media Center, it's as easy as selecting all files in the "Converted" smart playlist, and your "Lossy" smart playlist, and dragging them from the iTunes window into the Media Center window.
Once Media Center has imported them, you can then rename/move the files if you want or convert them to another format with ease. (though iTunes won't know where they are if you do that, and it only understands Apple Lossless)
After you have converted all your uncompressed files to Apple Lossless and imported them into Media Center, you probably want to delete the uncompressed WAV/AIFF files so that you don't have duplicates of everything.
