I seat about 7/8ft from the speakers and after running Audyssey, the channel levels are set as FL -5dB, FR -5.5dB, Center -8dB.
Why is the center set by Audyssey much lower than the mains? Shouldn't it be actually set the same or higher since it cannot produce the same SPLs? In some movies, I find that I have to set the center sometimes up to 0db,
Another question is do these values seem correct or should they be closer to 0dB? What is for example the -5.5dB referenced to?
Bdpf, there are no "correct" values. Those levels are simply adjustments, not actual volume levels. Those adjustments are made by Audyssey so that you DO get the same SPL at the main listening position. So the -8dB centre level setting would indicate that your centre speaker is actually ~3dB louder than your mains.
If you're not sure about the settings then your best bet is to double check them with an SPL meter. Or, you can disable Audyssey altogether and just use the SPL meter and make the adjustments manually. Either way, after you've level matched your speakers, simply adjust the centre speaker up or down to your own liking. If/when you come across material with poorly mixed centre channel content you may need to adjust again, no real way around that unfortunately
