I'm a big home theater guy and I disagree with millercarbon that a 2-channel rig in "phantom center" mode will sound as good as discrete 3 channels. It will sound nice, of course, but you will not have the directional aspect of a true center channel. Even though 2 stereo speakers can be made to "simulate" a center channel, the acoustics will still sound like 2 widely placed stereo speakers. You are also challenged with speaker location, so a 2-channel "phantom center" is not going to work well in my opinion.
I love the B&W D3 and I have the exact same speaker you are planning. It is my opinion that in HT, the front 3 speakers need to be exactly the same or as close as possible (i.e. same manufacture/series such as all D3). The surrounds do not need to be exactly the same, but they should be close. For example, I am still running old Focal Cobalt speaker for my surrounds and they do just fine. However, I have had different front speakers and it is definitely a problem when you have a center speaker that is voiced differently than left/right speakers.
Consider buying used? There is a 1-month old 805 D3 pair on audiogon for $4600.
As far as receiver vs separates. You will always do much better with separates, but it can be a little more costly depending. The B&W D3 will like a solid high current amp much better than a receiver. There is a huge difference in amplifier capability between a receiver and a dedicated amp. I would suggest looking at Outlaw Audio for a budget level separates. Their 7700 amp is conservatively priced at $2500 and will be significantly better than pretty much all receivers. Their 976 pre/pro is under $1k and have 4 HDMI 4K/UHD inputs. Unnless you really need 6 HDMI inputs supporting full 4K, this is a good deal. Otherwise, maybe look at the Emotiva XMC-2 for $3k. Or much better, look for a used Krell Foundation 4K.
There are other amplifier choices and pre/pros.
Like I said, separates will typically be engineered for sound quality, so technology upgrades may not be as fast. However, if your primary concern is 4K UHD and don't really care about bells and whistles (such as atmos, internet radio, bluetooth, etc.), the separates route will always yield better results.
I love the B&W D3 and I have the exact same speaker you are planning. It is my opinion that in HT, the front 3 speakers need to be exactly the same or as close as possible (i.e. same manufacture/series such as all D3). The surrounds do not need to be exactly the same, but they should be close. For example, I am still running old Focal Cobalt speaker for my surrounds and they do just fine. However, I have had different front speakers and it is definitely a problem when you have a center speaker that is voiced differently than left/right speakers.
Consider buying used? There is a 1-month old 805 D3 pair on audiogon for $4600.
As far as receiver vs separates. You will always do much better with separates, but it can be a little more costly depending. The B&W D3 will like a solid high current amp much better than a receiver. There is a huge difference in amplifier capability between a receiver and a dedicated amp. I would suggest looking at Outlaw Audio for a budget level separates. Their 7700 amp is conservatively priced at $2500 and will be significantly better than pretty much all receivers. Their 976 pre/pro is under $1k and have 4 HDMI 4K/UHD inputs. Unnless you really need 6 HDMI inputs supporting full 4K, this is a good deal. Otherwise, maybe look at the Emotiva XMC-2 for $3k. Or much better, look for a used Krell Foundation 4K.
There are other amplifier choices and pre/pros.
Like I said, separates will typically be engineered for sound quality, so technology upgrades may not be as fast. However, if your primary concern is 4K UHD and don't really care about bells and whistles (such as atmos, internet radio, bluetooth, etc.), the separates route will always yield better results.