Distance from speakers - 2-way vs. 3-way vs. ?

From my experience the ideal ratio for between speaker/from speaker distance is room size and speaker orientation driven. For many small room, long wall placement situations a near field approach may be ideal. The near field setting has the aforementioned ratio greater than 1. I also have found that the ideal ratio differs with recording, though an average ideal is what most of us strive for.

The many variables allow for divergent opinions.

Typically, you do not sit closer than the distance between the two speakers.

Per Schubert, there is a distance at which a 1st order crossover theoretically maintains phase coherence - it will vary with the physical properties of the cabinet/drivers - but it's hard to otherwise generalize.

As to extreme near field use, single driver and/or concentric driver (see KEF uniQ) systems are one way to dance around the issue.

Marty

Not really, crossover design has more to do with it than number of drivers.