Avantgarde Uno 2.0, 2.1

No harm in trying it both ways. But, it is not necessarily the case that the best orientation is all drivers in phase. For MANY speakers, the best integration is with a driver out of phase with respect to the other. This is dependend on the design, particularly the crossover.

I like the Duos myself, but I too find there are problems with the woofer. I doubt that it has to do with the woofer being out of phase. Woofers are quite hard to integrate with horn upper frequency drivers. Many horn systems eschew really deep bass in favor of faster drivers that can keep up with the horns. Perhaps driver transient response is an issue, perhaps something else. I found the bass on the Duo a bit uneven, such that certain notes seem to be a bit overemphasize and bloated. But, like EVERY speaker, compromises have to be made; on balance, the Duos are quite nice speakers.

Locational time delay might be a factor in integration, but, having experimented with horn systems, it is usually a minor consideration. You can move the bass driver much closer to the listener and if the bass driver is not well suited to the task, it will still sound slow or lumpy or whatever. The particular signature of horn drivers is quite hard to integrate with woofers, particularly where an emphasis has been placed on getting really deep bass from the woofer. Most decently integrated horn system have woofers in bass alignments that don't really allow for deep bass--e.g., horn loading or onken bass reflex--unless truly giant cabinets are used.

Like all systems,Avantgarde speakers reflect a particular set of tradeoffs, the best one can do is optimize performance--particularly placement of the speaker.