It could be the file format. Go to iTunes "preferences" and import CD tracks using aiff, wav (at higher sample frequencies) or Apple Lossless. MP3 with default settings is not hifi, and aac is a little better. If you like those last two formats because of considerations of file size, choose the higher sample frequencies. CD is 44.1 kHz, 16 bit. If you make a copy at the same spec, it should sound as good as the CD itself from most CD players.
I still think it is most probably the low-res default file format, James. Assuming WBD is happy with the stereo.
WBD - just experiment and find out what you have to change so that it no longer "sounds like crap". Is anything OK through the Powerbook? Like CD?
iTunes is one of those programs that makes itself the default for audio files, and then uses low-fi default settings - unless you tell it otherwise. The old Apple CD Player was better from that point of view.
Guys - thanks. I think it must be the cable or the output jack on the powerbook. I will change the cable (it has to be a Y cable from the single headphone out jack to the RCA inputs on the amp. The amp and speakers are fine - so that is not the problem. And when I play regular CDs from the Mac, the sound is not great, either, so I assume it is not the sampling rate or the format. Will keep you posted.
That is correct. The cable James refers to (which does not have to be from Radio Shack) has a mini-jack at one end, which plugs into the "Audio out" socket (with the headphones symbol) of the computer. The other end of the cable has whatever the home stereo system takes as an input. This could, for example, be another mini-jack, or, more likely, two RCA plugs (also known as "phono" plugs).
There are two other options I can think of.
1. A newer 17" powerbook has digital audio out, as a mini-jack socket that also takes an optical cable. If your home stereo has optical digital input, you can use that, but need to choose the correct optical cable to fit both ends; the computer and the stereo.
2. Apple Airport Express. You need an Airport card in the computer. You then have the same option - either analogue out or digital optical. I have one of these. It is really neat.
In both cases, for the digital connection, the sound is as then as good as the Digital-to-Analogue-Converter in the stereo system allows, I think.
I think the newer powerbooks have a proper line out but the older ones (like mine) do not. Using the headphone output will not produce good sound as noted by the original poster. The solution I have adopted is an iMic which costs about $30.