I've got a Peugeot 407SW with the JBL system (with subwoofer in the boot
wall), but I'm a little disappointed with it. There is loads of base and
power, but the sound overall sounds a bit flat and harsh to me - certainly
not a rich, high quality sound.

Trouble is, I'm not sure where to start with any upgrades. Any advise about
where to look first would be appreciated - will upgrading speakers be
pointless without a better head end? Is the quality of the sub woofer likely
to be suspect? etc etc etc.

Vague I know, but even a pointer to who could help would be apreciated.

Thanks,

Mark