These are not the same size of amplifier: NAD M10 V3 has roughly 3.3x the power of NAD D 3020 V2. That is about 5.2dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | A | NAD M10 V3 has more power - 100W against 30W into 8 ohms. That is about 5.2dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Noise floor | B | NAD D 3020 V2 is the quieter design on paper - 98dB against 90dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board. NAD M10 V3 goes higher - 192kHz against 96kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only NAD M10 V3 has AirPlay 2, Roon and BluOS. |
| Use with a TV | depends | Only NAD M10 V3 has HDMI, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only NAD D 3020 V2 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | NAD D 3020 V2 takes up about 76% less shelf area (146cm² against 606cm²), and it is 30mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | NAD D 3020 V2 costs less - $499 against $2,499 at list. |
| Watts per dollar | B | NAD D 3020 V2 is the cheaper watt - about $17 per watt against $25. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD M10 V3 B NAD D 3020 V2
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?
NAD M10 V3 is ahead, but on only 1 of the measured areas, and it costs about 5x the price. That is a lot of money for a narrow margin - NAD D 3020 V2 is the sensible buy unless a specific feature above decides it for you. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - NAD M10 V3 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 30 watts is already more than most people ever use, and the extra 70 watts would be headroom you pay for and never hear. If this sits under a television, NAD M10 V3 is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
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.