Just wondering what are some of the best speakers I could connect to my YAMAHA DSP AX640 SE AV AMP thanks

PMC AML1's.

Best to have a listen to numerous makes and models and see which you prefer to be honest (budget and size will also need to be considered). Personally, I would always go for B&W speakers, but then I have had B&W's of differing shapes and sizes for years, so I am a bit bias - they're customer service cannot be beaten either.

There are of course lots of other brands, Monitor Audio seem to do well in the reviews, as do KEF, Dali and some Mission models.

The only way to know though is to listen to what is a available that fits your needs and budget

Due to space constraints I have just added a set of Kef3005's to my Yamaha AX-620 & the sound is incredible despite their small size. The 250W Digital Amplifier in the Sub-Woofer gives great control. The sounfdield from the Satellites is very open, detailed & it comes to life at higher volume levels. Try & audition if you can, for £595 all in you will find them hard to beat.

Obviously depends on your budget.

I've got some Q-Acoustics 1010's and they're fantastic.

The full 5.1 Q-Acoustics kit is around £500.

http://www.q-acoustics.co.uk/compact_bookshelf_speaker/

They've won awards everywhere!