Check out their site. Not really digital - I think analogue switched digitally.
As they say: "The Reference 9 SE incorporates an improved power supply board with a low-ESR capacitor bank. Further enhancements include a separate switching power supply for the analog front-end, ..." and from the 6Moons review: (this) "amplifier technology is based upon the principle that a power oscillator can be modulated by an audio signal to produce an amplified audio signal obtained with a reconstruction filter but without the bandwidth limitations of a fixed frequency carrier-based conventional PWM control. It uses a high-performance analog modulation technique and a close-loop control system. Therefore NuForce refers to its audio amplifier as analog switching amplifiers."
One of the more pleasant surprises I've had in this hobby .
As they say: "The Reference 9 SE incorporates an improved power supply board with a low-ESR capacitor bank. Further enhancements include a separate switching power supply for the analog front-end, ..." and from the 6Moons review: (this) "amplifier technology is based upon the principle that a power oscillator can be modulated by an audio signal to produce an amplified audio signal obtained with a reconstruction filter but without the bandwidth limitations of a fixed frequency carrier-based conventional PWM control. It uses a high-performance analog modulation technique and a close-loop control system. Therefore NuForce refers to its audio amplifier as analog switching amplifiers."
One of the more pleasant surprises I've had in this hobby .