I've got the Bose speakers fitted. I've thought that perhaps it might be possible to get an after-market head-unit that allows the sound to be better controlled...
...I've found that to get the music sounding right when driving, I have to supress the treble otherwise it sounds a bit bright. (Probably due to the way your ears compensate for the sound of the engine). The speakers are fine, just the level of control over the sound is limited to simple Base/Treble and Audio Pilot (which in my view doesn't work very well). In my previous stereo, you had control over what frequencies were boosted, and could easily select different equalisation pre-sets. The quality of the components is fine - there's no boom or resonance, so I think they're very well matched to the car - it's just the lack of fine control which is a pain.
I'd agree with Dreamcar, that it might be better to get the factory to fit the speakers. If you find any decent alternative to the standard head-unit, let me know!
Then again, Listening to Dreamcar's PCM system with Bose yesterday, I thought it sounded better than mine (though I'll have to get some Chris Rea out to compare
), so it might be the CD-24 which doesn't have as good pre-amp output.
One last thought - the Speakers / Amp are Bose.. the head unit is Becker, isn't it? I'm not sure where the Bose stuff stops and the Becker kicks in.