According to the technical spec from Philips site, the DVDR890's only got 1 digital audio output, ie. it doesn't have built-in 5.1 surround sound decoder. Does your Cambridge system has such built-in decoder, like dolby digital and/or DTS decoder? If it doesn't, then you need to get an external decoder or an AV receiver with built-in decoder.
As for the region thing, you can get a <A HREF="http://www.kelkoo.co.uk/b/a/sbs/uk/dvdPlayers/keyword/DVD+r+890/type/DVD+Player/manufacturer/Philips/category/consumer/127701.html" target="_new">multi-region version of DVDR890</A> if it matters.