I'd pretty much assumed that it was basically due to something that I did, but I guess you're right that it could have been an equipment fault. Perhaps I should investigate that avenue further...
I did have the gains at a fairly reasonable level, which is why I'm scared of doing it again!
0db is pretty bloody loud, by my standards, and if I'm the car by myself, it doesn't usually get above -10db. When some friends are in the car they sometimes crank it all the way to 0db. But I never noticed any distortion. Mind you, the distortion caused by the damaged speaker was inaudible in many kinds of music as well.
Also, when you say the speaker was "blown", can you be more specific? Did you remove the speaker and find out exactly what's wrong with it? Fused coil? Torn surrounds? What?
It sounded strange playing brass quintet music. Stranger than it ought to, that is!
Seriously, I don't know exactly. After some experiments, I figured it was the medium sized driver (the one about 60mm across, in a 3way 6x9), but I haven't pulled it to bits, and there was no damage I could see with a casual visual inspection. Maybe I should just send it back to the manufacturer and hope for a refund, rather than dissecting it.
Richard.