Hi Gel
First of all, are you sure you want to spend this amount of money?
If you are, it's imperative that you hear different options at different price points....I think the amp is simply surperb, so I would look at what different speakers give you in terms of vfm and presentation.
1. How important is 2 channel to you....this will determin how much to throw at the left and right channels.
2. For AV, go for the best centre and sub you can afford, even if you spend less on the rear channels (imo)
3. If you are at this level, you must hear the New Kef Refs....the Ref 1s would be plenty, if AV makes up most of your listening. The R Series are also worth a listen, but are not in the same league. The Arcam works well with both. FWIW. My AVR600 can drive the older Refs, no problem....and the 850 is better again.
4. JL Audio subs are worth checking out.
Make sure that you are prepared to spend the money before you listen to either of these options...as they will blow your socks off!!