CD ripping

Thanks everyone, great responses!  
 
Guess I need to do some ab tests and work out what to do.

I'm minded to re rip my collection, back up and get rid of all the CDs.  But will test first.

Update.

looks like considerable number of my files, on itunes, are AAC @ 128 and AAC @ 256.

So I used dB to rip 3 versions of the same track 

flac 5
aiff
apple losless

have to say found it hard to tell the difference and I thought my "ear" was pretty good. For example, I find poor recordings hard to listen to.

i will be re ripping as many of my older files are lossy using dB.

thanks again for the advice, really helpful. 

Steve 

Sevs, thanks for guidance - I'm in process of doing that.

cheers