Naim has used Class D here and there, in its Mu-so wireless speakers and in the car audio systems the company makes for Bentley Motors. But Naim’s traditional home audio products have stuck with Class AB. This includes the brand’s pricey New Classic range of high-end electronics, as well as the popular Naim Uniti family of streaming amplifiers
Naim did go this way with the Tripath amp modules in the n-Vi back in 2006. A simple way to get 5 channels of amplified audio into one classic sized box.
Buggy firmware issues aside, it certainly had the Naim house sound.
Class D has come a long way. The PMC Active Modules I now use in the twenty.5 23i were a steal at the price - half of what I got for my 300DR.
I hate to say it, but the combination sounds better too.
G
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Why?
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Class D amplifiers have historically been criticized for their sound quality, particularly in the early days of the technology. However, advancements in design, component quality, and digital signal processing have significantly improved their audio performance. Modern Class D amplifiers can rival Class AB amplifiers in terms of sound quality, especially at higher power levels, where their efficiency becomes a significant advantage.
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Class D amplifers are analog.
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Without going too far into the details: basically, a digital (Class D) amplifier takes an incoming analog signal and converts it into a digital representation comprised of pulse widths. Although there are several different design variations, Class D amplifiers are essentially switching amplifiers or Pulse Width Modulator (PWM) designs.
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A Class D amplifier is NOT Digital.
From What Hi-Fi;
The ‘D’ doesn’t stand for ‘Digital’, in fact, none of letters used to identify the classes of an amplifier actually stand for anything specific. Without going too far into the details, a Class D design takes an analogue input and turns it into a PWM (Pulse Width Modulation) signal where the peak of the signal results in the widest pulse and the trough, the narrowest. Class D amplifiers always have an output filter to take out the high-frequency noise generated by the conversion process. The quality of this filter has a great bearing on the overall sonic performance.
The major plus point of Class D is that it is very energy efficient. A typical Class A design tends to be around 30% efficient. Class A/B roughly doubles that while Class D amplifiers almost triple it. That means proportionately lower power consumption and less heat. The reduced amount of heat lowers the heatsinking requirement considerably, allowing the manufacturer to make the product smaller (and lighter). The sheer efficiency also allows Class D amplifiers to deliver huge power outputs for their size.
DG…
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Assuming class D is digital is common error, based on the ‘D’ of Class D, which actually doesn’t stand for anything. Class D is not digital, it doesn’t convert into digital. It does use Pulse Width Modulation where the peak of the wave produces the widest pulse and the trough of the wave produces the narrowest, but that is not digital.
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I always understood that class D gave the music extra depth whilst class A gave the classical analog sound and A/B gave one an analog sound with an added bounce or boogie factor - but then again what do I know?
.sjb
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I enjoyed a Nova PE for a while, very good sound with taught and controlled fast bass with detail soundstage. Nothing to not like at the used prices they go for.
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And. PWM is digital. 
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I suppose here we’re down to definitions of digital! It is not the same as the digital encoding of music as introduced with CD and continued to this day through ripping of LPs., streaming, downloading music files.
Nope, it’s not. It’s analog.
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Nope its nt
Martin
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I suspect that is the reason people think Class D isn’t digital.
Yes pulse width modulation is certainly a digital technique. Chat GPT explains it like this.
Pulse Width Modulation (PWM) is a digital technique used to simulate analog signals. It achieves this by rapidly switching a digital signal (on/off) at a fixed frequency while varying the duty cycle—the proportion of the “on” time to the total cycle time.
Why PWM is Digital:
• The signal itself is either fully on (1) or fully off (0), which are discrete digital states.
• The modulation occurs in the timing of these states, not in the continuous variation of voltage or current.
How PWM Simulates Analog Behavior:
• By varying the duty cycle, the average power delivered to the load changes, creating an effect similar to adjusting a continuous analog signal.
• For example, a 50% duty cycle results in an output that, when filtered (e.g., with an RC circuit), appears as half the maximum analog voltage.
PWM is widely used in applications like motor speed control, LED dimming, and audio signal generation because it combines the efficiency of digital electronics with the flexibility to approximate analog behaviors.
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Not my cup of tea but I have to say that the CI-Uniti 102 is interesting… For instance it could be an all-in-one solution for he kitchen or rooms where you want something small and discreet with good audio quality (let’s not forget its DSP capabilities that can be very handy, espcially if you don’t want to treat a room for aesthetic reasons).
Of course I’m not comparing these products to OC and NC (it would be pointless), they are indeed on different league and they aim at a very different target in the first place.
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Isn’t science and technology grand