I've learned that setting the rear speaker delay to a correct setting for your "sweet spot" (your sitting position) is really important in getting the best sound out of a 5.1 audio system.
If the sounds from the front and rear speakers aren't hitting your ears at the exact same time, they can cancel each other out, making a significant difference in the quality of the sound.
For movie soundtracks, due to the nature of the sound mix, I don't find this quite as important or noticable. But for the kind of material we listen to on super audio discs, it's very noticable.
I got good results putitng on a surround music disc and adjusting the rear delay settings until I got the best sound. I didn't find it very hard to quickly identify the appropriate settings. (It's easy to hear when things are slightly out of phase.)
Note: My player allows me to make the delay setting in terms of how far each of the speakers are from my listening position. But I found that my ears led me to different settings than I got adhering to strict speaker distances. Since my ears are what matters, that's what I went with.
I've found for me personally thats the best way to setup my system, I have also found that not all recordings are the same so I'm alway tinkering with my system to get the best possible sound stage.
I have found that Elliot Sheiners mixes are pretty darn cosistant, this man really knows his stuff, personaly I think he's the best digital mixer out there.