R, the "best" is to angle every speaker so the center of the tweeter is pointing directly at the listener's ears. That's the theory. In practice, it's hard for several people to share one pair of ears. Besides, most speakers have a fairly good dispersion pattern, so it's not critical.

Mine are toed in somewhat, and my center, even though it's below my screen, is not angled up. it's just barely below sitting ear level. There is definitely a sonic difference between standing and sitting, so there is truth in the angling.

Larry
www.fineelectricco.com