Multi-channel stereo sends the same signal to all speakers, so it's not surprising that the rears and sides are too loud. It can be an interesting effect on older recordings like some Beatles material but for modern material it can require tweaking the levels of the surrounds, but that could mess up the levels for movies. There are usually better options for upmixing 2-channel audio to surround like Neural:X on new AVRs or PL-II on older AVRs. It's a matter of trial and error as to what one likes but I generally leave 2-channel music on Stereo as my AVR does not have Neural:X. Whether you like Audyssey or not again is a personal choice. Direct mode will by-pass all processing while turning Auddyssey on and off will leave other features enabled. Pay particular attention to vocals when experimenting. I like Audyssey on for movies but usually disable it for stereo music. For multi-channel music you may find it better turned on. If you can stream Dolby ATMOS music that will give you a much better idea of what multi-channel music can do vs upmixing stereo tracks. Its interesting, when I do use Audyssey it defaults to Dolby Atmos even though my receiver does have Neural:X. I play these apps through Xbox-X. But even with the Dolby Atmos songs on Amazon Music the sound only plays through my front three, subwoofer and height speakers.