Soundstage's measurements don't show the upper treble off-axis drop off to be quite as severe, although it is there. Those who want to hear very high treble should listen near direct axis. The thing is, most of the people in the market for a speaker like this, older men, don;t have very good hearing in that range anyway, so who is really being affected by this? What's more, there isn't that much important content in that range anyway. One other point is that higher frequencies are less subject to room reflections, so a dead room vs lively room wouldn't matter as much for frequencies in this range. Another thing, the Performa F228Be isn't
that much better in very high frequency dispersion.