Mano, are you sure that Mirage "recommends" tri-amping? The manual states that biamping or triamping "CAN further enhance performance" (emphasis added). My instinct would be to interpret "can" as "might," not as "will." And it would seem very conceivable to me that the three sets of connections are provided simply to give the user flexibility in choosing the amplification configuration.
Regarding the question of how much of a power increase passive biamping (or triamping) may provide, in typical situations the power that can be delivered by a single amplifier is limited by voltage swing capability (i.e., by the onset of clipping), not by current capability. Since, as Elizabeth pointed out, passive biamping (or triamping) requires that all of the amplifiers output a voltage swing corresponding to the full range signal, it will not typically result in a significant increase in power capability, compared to the power that could be provided by a single amplifier of the same rating. There may be a small increase in power capability if the design of the amplifiers is such that the reduced current demands on each amplifier in the biamped or triamped configuration result in increased voltage swing capability.
Keep in mind also that if you use different amplifiers for the lows and the mid/hi's, you have to choose amps that have matching gains, or provide external attenuation to match their gains. And be aware that if the amp you choose for the lows is significantly more powerful than the amp you choose for the mid/hi's, much of the power capability of the higher powered amp will be wasted, because since both amps will have to handle the full range signal, the volume level you can achieve will be limited by the clipping point of the lower powered amp.
Certainly passive biamping can SOMETIMES result in improved sonics, if not a significant power increase. But as several others have suggested, my advice would be to buy a single high quality high powered amp, and avoid all of these complications.
Regards,
-- Al
Regarding the question of how much of a power increase passive biamping (or triamping) may provide, in typical situations the power that can be delivered by a single amplifier is limited by voltage swing capability (i.e., by the onset of clipping), not by current capability. Since, as Elizabeth pointed out, passive biamping (or triamping) requires that all of the amplifiers output a voltage swing corresponding to the full range signal, it will not typically result in a significant increase in power capability, compared to the power that could be provided by a single amplifier of the same rating. There may be a small increase in power capability if the design of the amplifiers is such that the reduced current demands on each amplifier in the biamped or triamped configuration result in increased voltage swing capability.
Keep in mind also that if you use different amplifiers for the lows and the mid/hi's, you have to choose amps that have matching gains, or provide external attenuation to match their gains. And be aware that if the amp you choose for the lows is significantly more powerful than the amp you choose for the mid/hi's, much of the power capability of the higher powered amp will be wasted, because since both amps will have to handle the full range signal, the volume level you can achieve will be limited by the clipping point of the lower powered amp.
Certainly passive biamping can SOMETIMES result in improved sonics, if not a significant power increase. But as several others have suggested, my advice would be to buy a single high quality high powered amp, and avoid all of these complications.
Regards,
-- Al