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The X25s are best avoided as they are not good speakers by B&O standards and (conversely) seem to fetch reasonably high prices on eBay. Best to do a search on eBay and see what is available, I am using my Beosystem 5000 with my Beovox S45-2's which are a good choice amongst the earlier B&O speakers because they sound good, do not suffer from 'foam rot' and are not too big which means they are relatively 'wife-friendly'. Threre are plenty of other good choices though (including the redlines) , most of which will be available for £50-100 at most and quite possibly much less.
It's a good idea to replace the crossover capacitors on any 20-30 year old pair of speakers, there are plenty of threads about this.
If you already have speakers you want to use suitable cables are freely available.
Simon