These are not the same size of amplifier: NAD M10 V3 has roughly 2.5x the power of NAD C 328. That is about 4dB, 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 40W into 8 ohms. That is about 4dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output barely increases (100W and 40W). |
| Noise floor | B | NAD C 328 is the quieter design on paper - 100dB against 90dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board, but only NAD M10 V3 handles MQA. |
| Streaming | A | Only NAD M10 V3 has AirPlay 2, Roon and BluOS. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only NAD C 328 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | NAD M10 V3 takes up about 55% less shelf area (606cm² against 1349cm²), and it is 32mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | NAD C 328 costs less - $699 against $2,499 at list. |
| Watts per dollar | B | NAD C 328 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 C 328
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 3.6x the price. That is a lot of money for a narrow margin - NAD C 328 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, 40 watts is already more than most people ever use, and the extra 60 watts would be headroom you pay for and never hear. Think about the whole system: the roughly $1,800 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.