This is quite easy to take apart, you just unfasten the screw underneath and it slides out backwards. You will have to unplug the speaker connnectors but this is easy enough, oh, and there will be a bit of wire from the electronics which is stapled to a piece of aluminium foil on the underside of the top cover that you'll need to unfasten. I find

Testing testing...............

They are reasonable speaker, but they don't fetch all that much on EBAY, I would expect it has something to do with shipping costs. Someday I'm going to replace the electrolytic capacitors in one set of mine and compare them against the unmolested pair. I've got most of the others of that range, and in some ways the Beovox 4000 are better

Looking at your old amp and the specifications, you should be ok. You do have to bear in mind that a Japanese power amp tends to be seriously optimistic and you might even find that your Beocentre 9500 is at least as powerful as your old Sony. I could tell you a few stories about just how optimistic the Japanese power ratings can be.