Speaker and Receiver help

I currently have bower and Wilkins 683s I also have the bowers and Wilkins HTM61 center. I have the option of the bowers and Wilkins asw610 sub or a Def tech Supercube 8000. I need recommendations for the AVR or a separate powered amp. And I need recommendations for rear speakers and if I need to add the additional surround for 7.1. Lastly which sub do I use?
If you are going separates, then you will need a quality preamp/processor along with the separate power amp(s) to drive the 5 or 7 speakers. (ignoring the intuitive requirement for additional quality ICs to connect them)

-- This big advantage is that you can eventually replace the AV pre-pro as the CODECS change (that is the "disposable") without trashing the rest of the system. Assuming that you buy the quality power amps used, their build quality and power supplies will easily best those in any AV receiver = superior performance -- The qualifier is that superior performance is going to cost you ..... You get what you pay for in this hobby.

If you are going with an AV multichannel receiver, it's build quality and audio performance capabilities can vary greatly. In my experiences that support the reviews, the ARCAM and the CAMBRIDGE lead the pack for that superior performance . (I had the top CAMBRIDGE before I went to separates above) Google their reviews .... Highly recommended units in their unibox genre.

Advantage : cheaper all in one unibox ..... Disadvantage: quality (emphasis added ) separates best the AVR in build quality and in performance but at a price.

One last qualifier as an FYI: If you value two-channel listening as the primary, but you also want multichannel HT audio capabilities; then first get a quality 2 channel integrated amp with a direct pass-through from the AV separate preamp/ processor unit to run the LF and RF channels when you switch over to multichannel movies etc.