Hi, Since getting my PowerBook in February, I've been listening to a lot of music from the internal soundcard (as opposed to one of the Digidesign soundcards at my disposal). I know it's not ideal, but sometimes it's just easier to plug your headphones in and get on with what you've gotta do, rather than having cables everywhere and having to mess around with the atrocious Digidesign CoreAudio Manager. So, does anyone know what the limitations of the internal soundcard are? According to AppleHistory.com, the PowerBook headphone jack is capable of 16-bit at up to 48KHz, however, in my System Profile I see this: The main reason I'm asking is that I often have to listen to 24-bit .wav files in Quicktime (due to the fact that iTunes won't even add them to my library). So... is Quicktime simply converting to 16-bit on the fly? Or is this internal card actually capable of playing back 24-bit files? And if so, why will iTunes not add 24-bit files to my library? Isn't iTunes, uhhh, 'built' on top of the Quicktime 'playback engine'? Also, I've never come across the term 'Bit Width' before. Can anyone explain what it is and how it relates to audio? Tim.