The stated-load related performance is consistent with the size of the capacitor bank - doubled in the monos. The power supply in the standard stereo unit looks similar to the power supply in the Signature monos shown in the picture over at 6 moons. It used to be that a mere 4 ohm load was considered demanding.
There can be other reasons for choosing monos such as a pre-existing cable set or aesthetics.
Bob
There can be other reasons for choosing monos such as a pre-existing cable set or aesthetics.
Bob