How do I power my 800D(3)s

Sell the speakers, give the money to charity and buy a Sonos 3. 
On a more serious note, at this level you should work with a pro. 

@Matt-gf,
There are lots of members here on Audiogon that can give you some very good answers to your questions. The problem is most answers will come from their personal preferences and no one answer is correct or wrong. Just like if you work with three different professionals you will probably get three different answers.

Here are a few options to consider:
Do you prefer the sound of tubes or solid state?
Do you want an integrated amp or separates (amp/preamp)?
If you want separates, do you want one amp or monoblocks?

The speakers you mentioned will work with 50 to 1000 watts and are 90% efficient, so I don't think you can go wrong with any answer you come up with from above.
In addition to what I have mentioned, what type of budget are you working with?

Best regards...

Classe certainly makes fine amps, but as noromance notes, you should have a dealer involved with setting up your speakers and demoing a range of appropriate amps *in your room.*  The one you like the best is the best amp for you.

Given your mention of a streamer, I encourage you to seek out the best possible source material and source components.  That's another job your dealer should help with.   

Congrats on your purchases; enjoy!

As others have noted the dealer you purchase the 800s from should help you find the appropriate amplification for the speakers and your room and offer in-home demos. I wouldn't buy a speaker in that class from a dealer that wouldn't accommodate you in every reasonable way.

Personally, I would go with a pre/amp combination with at least 200 watts for the 800s. I love power and I have never heard a speaker that didn't sound better the more high quality watts that were sent to them.

You will enjoy the buying experience and the speakers more when you deal with a good dealer. Good luck and have fun. You are getting an outstanding speaker.

Cheers,

Scott

B&W and Classe have a corporate connection of some sort, which is why they are so often shown together.  Classe is good, but there may be better options.