B&W 804 + AVR850 or 550 in a 5 channel setup with a bread and butter sub.

Absolute newbie here. please be easy on me. merci beaucoup.

I heard the 804s in the Magnolia store and was absolutely blown away. I love them.
About me: While I truly enjoy the music of the 80s and the 70,  pop and rock, I am not an opera or jazz fan.

Based on your experience or knowledge would you recommend the B&W 804 + Arcam's AVR850 or 550 in a 5 channel setup with a bread and butter subwoofer.
Also, what center speaker and what speaker wires would you suggest?
Budget 20K
It’s not my money, so I throw some caution to the wind.  But, I’ve owned the 804’s and that Arcam will not be enough to drive them.  It will sound fine at lower listening volumes and probably not noticeable while watching movies, but when you turn it up, you’ll be left scratching your head.  Frankly, you’ll be missing out on how those speakers are supposed to sound.  

If you’re shopping at Magnolia, you should be looking at the McIntosh MC452 to drive those, then looking for a lesser expensive 5 or 3-channel to drive the center and rears.  

Again, not my money or budget, but I would gravitate towards a less expensive home theater preamp.  Marantz makes quality HT preamps, that sound pretty damn good as a 2-channel setup, then dump more of the budget into a larger 2-channel and a less expensive 5 or 3 channel.  

They carry REL subs, you can not go wrong with that selection.  Per the center, I would go with the B&W 700 series center.  Not the same model line, but less expensive.  Some may say “it needs to be matched, timber and such”, I disagree.  I ran the 804’s with a CM series center, sounded fine.  

Per wiring and interconnects, this a rabbit hole that has no end.  I would encourage you to locate them second hand, as the discounts can be excellent vs. MSRP.  Audiogon has an abundance of well priced, good cabling.