Right guys thanks for all the advice, it would appear these are worth spending some time on.
Andre I'd like to take you up on your kind offer of help in sourcing the parts. The first job I suppose is to remove the crossover board. I'm assuming that to desolder the 6 wires I use a soldering iron which I don't have, so if someone can recommend a soldering iron starter kit (nothin to fancy) that would be suitable for DIY audio work then that would be a great start.
Lots more dumb questions to follow.
Rich
Source: Squeezebox Touch, Chinese AK4396 DAC, Pioneer PL-112D + Shure M75ED type2, Pioneer PD-7700 CDP
Amp: Sansui AU-505
Speakers: Ditton 44's