Selecting Rear Surrounds for 5.1 system

I went over the Best Buy meantime and asked the Magnolia room person the same. He said it’s best to balance the room with B&W 704 or 705. He was against using KEFs or Polks or Martin Logans in the back when 702s were in front. He said that they perform quite differently. They sell KEFs and MLs also.

Of course he’s gonna say that because he wants to sell you more speakers and that’s the easy layup answer. I worked at Magnolia briefly and have been to several others, and they are mostly just hacks who have very little personal or real experience in high-end audio. When I cobbled together my HT system I used my wife’s Polk monitors from the 90s that were not in any way matched to my fronts and they worked perfectly fine for creating a very immersive movie experience. If you wanna blow a big wad on the rears have at it, but my opinion and experience is that it is not necessary. Save the money there and put the rest toward getting a better (or second) sub or center speaker where it’ll make a much bigger difference.

i sorta agree that unless you're listening to multichannel music the rears are less critical, but all things being equal i'd stay with b&w for them--their 707 models aren't too expensive and should work well.

OP, I found my way to 2 channel via my love for HT when I was growing up.  I prioritized having a HT right after graduating from College.  Was always told that you had to match your speakers, really buy the same brand, line for things to sound right, correct.  As I got into 2 channel my focus shifted, I prioritized my 2 channel set up over my HT though they share the same space.  That meant shifting away from matching speakers and finding 2 channel fronts that I loved for 2 channel, working for HT was an afterthought.  Guess what, everything still sounds great in my HT.  My fronts are a different brand, different type of tweeter than my center / rears and Atmos speakers.  The rears are my old towers, only because I had them, wasn’t worth the hassle of selling them and was easier to repurpose than store them.  Ceiling Atmos speakers are yet a different brand.  I do think using the room correction on your HT Receiver is key.  I have an Anthem MRX1140 but I did have a Marantz, generations older than your model prior which did a great job blending the hodge podge of speakers together.  Get a descent set of used speakers, I’d roll more with best value, bang for the buck, build quality over trying to brand / voice match.  If you are into 2 channel, I took the opposite approach to that, I built the 2 channel as a separate, stand alone system that doesn’t need to share anything from the HT chain.  I found that approach for 2 channel was key, system matching everything in the chain, pre, streamer, DAC, Amp, speakers.  Polar opposite to how I approached my HT set up once the space morphed into HT and 2 channel listening.  

These will let you stay B&W. They have great mounting options.

https://www.ebay.com/itm/186824400881?chn=ps&_trkparms=ispr%3D1&amdata=enc%3A1Nalu8J3uRkKDaCvLHW84qA29&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=186824400881&targetid=2320093655185&device=c&mktype=pla&googleloc=1018594&poi=&campaignid=21222258394&mkgroupid=164713660992&rlsatarget=pla-2320093655185&abcId=9408285&merchantid=114759509&gad_source=1&gclid=CjwKCAiAmrS7BhBJEiwAei59i4PyceoQNwOkv2qLDqiEjAPLO3Ndgd33nkgoaAyUd3jLVo1E2D3xWhoCbtQQAvD_BwE

Hi OP:

The ideal surrounds have a lot to do with the character of the fronts.  If the fronts are very neutral it makes it very easy to pick among neutral surrounds, but B&W have their own sound characteristics.  I find that these traits are not usually damped by room correction so you should stick to B&W in general here to get the most immersive experience possible.

Best,

E