if you want the best sound quality yes you should go back and delete the tracks and import at the 256. but this will use more space. better sound quality bigger file.
I just love my new walkman and I have now put all my old cd,s into sonic stage and then transfered them onto my NWHD5.
All is well, for all the negitivity about sonic stage I think it is very good.
I do have a question however.
I have just realised that I have imported all my cd's at 64 kpbs (actrac 3plus). This means I can only transfer tracks to my nwhd5 at 64 kpbs.
I am worried that I am not getting the best sound quality whether that is on my walkman or simply playing from my PC with sonic stage. I also want to be able to burn good quality CD'S for the car from my libary.
Should I go back and import them all again at 256kpbs (actrac 3plus) or even as WAV files so I have the option of transfering tracks at 256?
So what is best 64, 256 or WAV?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic