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 | A | Rotel A10 MKII has more power - 50W against 40W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Rotel A10 MKII the better fit for a very large room, and NAD C 328 for desk or near-field listening. Match the amplifier to the room you actually have, not the one you want. |
| Speaker load rating | B | NAD C 328 is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| 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 | evenly matched | Both have a DAC on board with much the same capability. |
| Analogue inputs | A | Rotel A10 MKII takes more analogue sources - 4 against 2. |
| Room to grow | B | Only NAD C 328 offers preamp outputs and a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Rotel A10 MKII is Class A/B and NAD C 328 is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | NAD C 328 takes up about 17% less shelf area (1349cm² against 1633cm²), and it is 68mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Rotel A10 MKII costs less - $599 against $699 at list. |
| Watts per dollar | A | Rotel A10 MKII is the cheaper watt - about $12 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 Rotel A10 MKII 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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it.
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.