Thanks! I would if you don't mind
A good conventional speaker's perceived tonal balance is a weighted average of the direct sound and the reverberant sound, the latter being dominated by the off-axis energy. Typically the off-axis energy has a generally downward-sloping spectral balance because the tweeter is beaming up high. So in order to end up with a natural-sounding tonal balance, the direct sound needs to have enough high frequency energy to balance out the relative lack thereof in the reverberant sound, and we end up with an "in-room" curve which is gently downward-sloping. The direct sound is brighter than this net "in-room" curve, and the reverberant sound is duller.
With a "two streams" speaker, the reverberant energy is getting proportionally more high frequency energy, relatively speaking, because the rear-firing energy has a full dose of highs. So if we still have the "normal" amount of highs in the first-arrival sound, the net tonal balance would tend towards brightness. With both top ends being user-adjustable, we have the option of turning down the highs in the rear-firing drivers, or in the front-firing drivers, or maybe a little of both.
My personal preference is for both the direct and the reverberant sound to have a gently downward-sloping spectral balance, more similar to one another than what we would normally get from a pair of conventional speakers. To my ears, this results in a more realistic timbre. I am well aware of the argument that the reverberant energy should be more strongly downward-sloping to mimic the rolloff of the highs with distance, and have tried it both ways.
What I THINK is going on is this: With a good recording, the venue's reverberant field is ALREADY present, and its spectral balance is ALREADY CORRECT (rolled off in the highs) as it decays away into inaudibility. The job of the reverberant field in the playback room is not to MIMIC the venue's acoustics, but to PRESENT the venue acoustics which are already on the recording EFFECTIVELY. And imo in two-channel, this is best done by having a reverberant field that is spectrally correct, that is neither too strong nor too weak, that doesn't arrive too early, and that decays evenly and neither too fast nor too slow.