Hi Smaky, thanks for your input.
What I need to know, for my piece of mind is, could the careful fitting of a new head unit have kick started all of this off?
The new head unit works fine; it just displays a stanby LED when switched off.
I know about the permanent and switched positive feed issues, but the old Sony head unit never presented any problems; I just had to hold the power button down to switch it off completely.
The weird 'fishy' smell that cropped up just as the engine died the other night (travelling at 60 mph and with no warning whatsoever) to me, is a bit of a worry; fairly obvious that something got hot!
As I mentioned in my other thread, we couldn't see anything obvious; all of the main fuses are intact; the only fuse I found o/c was a brown 7.5 amp under the drivers side fuse cover.
It is one of the fuses that sits in a small cluster of other fuses above the main bank of fuses (quite hard to see unless you've got you head right down in the footwell) Because it isn't listed on the rear of the cover, I don't know what circuit it sits on, or whether it's got anything to do with my current problem?
My mechanic called on Saturday afternoon, he also mentioned that the battery may now need replacing given the stresses that have been placed on it over the last week or so.
He can't start working on it until Tuesday, but did a few quick checks...
As the AA guy found, with the engine cranking, there is no signal reaching the HT packs and the fuel pumped can't be heard priming with the ignition on.
The AA guy mentioned that he'd once been called out to a 3.0L 164 where one of the HT packs had shorted to earth, causing a similar problem.
As you say, the alternator had crossed my mind too.
I'll pass on your check list to the mechanic (he's not an Alfa specialist, but does look after a lot of high end cars) and guess, take it from there!
I could really do without a huge bill just before Xmas