Just a comment on timbre.
Once you finally try timbre matching, you'll generally know why it's so important. It may not always be a night and day difference, but it's always better.
Imagine that you know your Mom's voice, and she's standing right in front of you talking. Even with eyes closed you know it's her, in part because of the timbre of her voice. If you have five Mom clones, all standing at a 5.1 position (LF, C, RF, LS, RS) then you'll hear your Mom's voice sounding the same wherever her voice comes from. (Forget about the room anomalies for a second, okay?)
Now, imagine that your Mom is still the center channel, but your loud-mouthed aunt Betty is LF and LR, and your 11-year-old, squeeky cousin Emily is the LS and RS. If they repeat your Mom's words precisely, at the same time with the same pitch, will you still hear your Mom wherever the sound comes from? The answer is no, even if Betty and Emily are trying to imitate your Mom's voice.
Why not? Different timbre.
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