The first thing to do is forget the notion that stereo recordings must be reproduced with two channels. Recordings maybe mixed down to stereo as it is a better format than mono but it's no reason to insist they must be heard in stereo. Dolby surround does an excellent job and it enhances the listening experience.
It is crucial to set speaker distances as accurately as possible (small hand held lasers are ideal and far better than tape measures). Balancing levels is critical.
I recommend having all speakers from the same manufacturer and if possible the same series. Pre outs are best and identical
amplification is ideal as the last thing you want is each channel having a different "sound". Some home theatre systems allow you to turn amplification off and the massive power supplies are then ideal for surround processing.
Five point one is a good starting point, but adding two front wide speakers and two rear surrounds really encases you with sound. That's nine point one and adding four Atmos speakers completes the package.
Four subs really makes a massive difference. I prefer to have them equidistance from the main listening position.
Another crucial consideration is adding super tweeters to each loudspeaker. The difference is so incredible it is unbelievable. The best way to describe it is the recorded sound disappears and you are there hearing sounds as they were recorded. Townshend SuperTweeters are excellent but the cost for multichannels is prohibitive. I've found that BatPure are ideal and they have a higher frequency range. They only have one output level, which is basically the same as Towenhend's position one.
Movies and music are spectacular.
I've mentioned this previously, but it's worth mentioning once more. Loudspeakers can be greatly enhanced by reducing sounds bouncing around in cabinets and contaminating cone movement. Lining the cabinets with sound deadening material and filling the internal space with sound absorption material works a treat,
