No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 30W against 35W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Speaker load rating | A | NAD D 3020 V2 is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| Noise floor | A | NAD D 3020 V2 is the quieter design on paper - 98dB against 82dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | NAD D 3020 V2 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | B | Cambridge Audio AXA35 takes more analogue sources - 5 against 1. |
| Room to grow | A | Only NAD D 3020 V2 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | NAD D 3020 V2 is Class D and Cambridge Audio AXA35 is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | NAD D 3020 V2 takes up about 91% less shelf area (146cm² against 1598cm²), and it is 122mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Cambridge Audio AXA35 costs less - $399 against $499 at list. |
| Watts per dollar | B | Cambridge Audio AXA35 is the cheaper watt - about $11 per watt against $17. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD D 3020 V2 B Cambridge Audio AXA35
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both amplifiers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
The usual trade-off: NAD D 3020 V2 measures better, Cambridge Audio AXA35 costs about 20% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Cambridge Audio AXA35 becomes the more rational buy.
What a spec sheet cannot show: how either sounds with your speakers, how the controls feel day to day, and what the app is like to live with - which is where most all-in-one amplifiers are actually won or lost. Power figures are the manufacturers' own and are not measured to a common standard, so treat small differences as noise. If you can hear both, that will tell you more than any row above.