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 | B | NAD C 388 BluOS-2i has more power - 150W against 100W into 8 ohms. That is about 1.8dB, which is a small step in loudness but real headroom on peaks. |
| Built-in DAC | A | Both decode on board, but only Yamaha R-N1000A handles DSD. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Analogue inputs | A | Yamaha R-N1000A takes more analogue sources - 3 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Yamaha R-N1000A is Class A/B and NAD C 388 BluOS-2i 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. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | B | NAD C 388 BluOS-2i is the cheaper watt - about $15 per watt against $23. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Yamaha R-N1000A B NAD C 388 BluOS-2i
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.