Thanks for the info guys,
I'm taking the car to an audio specialist on Friday to be checked out for the fault first. When I described it to him, he said it sounded like a dry solder joint or similar, so we'll try to isolate it to the amp or head-unit or speakers. If it's not from those, then it would have to be the wiring loom.
On the research side, I've had a look at a JL Audio 6 channel amp or an Alpine MRP-F240 which someone on Boxta.net had recommended. Sorry RandallNeighbour but if anything I'll go from my current CDR21 to a CDR22 (or 220 - as both are shipped to Aus). I really like the Becker head units.
Once that is in place, then I'll order in the rear speaker units from the US (I've not seen them for sale in Aus or fitted on any cars of my vintage yet, so that would make it pretty unique).
The Crutchfield site is excellent, but they won't ship outside the US, so we can use it for research, and then have to try and source locally. However ebay is a wonderful thing.
thanks again
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