I have been fascinated by sound reflection before . Let me add another observation.
To begin with, everyone owning a (Titanium) Powerbook will know that its tiny speakers point upwards. Thus using your Powerbook to play music to you before going to sleep, say, won't work too well if the Powerbook is sitting on a desk that's higher than your bed. Putting the Powerbook on the floor will greatly increase sound quality to a still poor but mildly acceptable level. Just make sure you don't step on it when you get up...
The thing I noticed when using iTunes at my office while plugging in the second screen is the following: The Powerbook's screen will gladly reflect any sound coming from the speakers if it isn't fully opened, i.e. at an acute angle. This way you can increase the amount of sound actually making its way to you – at the cost of not being able to use the computer. Still, this may come in as a handy alternative if you don't feel comfortable about putting your Powerbook on the floor or want to improve the sound while not using the computer part of the jukebox.
That said, at least with first generation Titanium Powerbooks, the speakers themselves are so tiny and poor that using headphones will be a better choice whenever possible. Newer revisions of the Powerbook seem to have better speakers. At least Jean's DVI-generation Powerbook has.
Received data seems to be invalid. The wanted file does probably not exist or the guys at last.fm changed something.