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 | Bluesound POWERNODE N331 has more power - 100W against 80W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Noise floor | A | Bluesound POWERNODE N331 is the quieter design on paper - 102dB against 84dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board, but only Bluesound POWERNODE N331 handles DSD. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Bluesound POWERNODE N331 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | Bluesound POWERNODE N331 takes up about 36% less shelf area (418cm² against 651cm²), and it is 106mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Bluesound POWERNODE N331 costs less - $1,299 against $1,499 at list. |
| Watts per dollar | A | Bluesound POWERNODE N331 is the cheaper watt - about $13 per watt against $19. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Bluesound POWERNODE N331 B NAD C 700
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?
Bluesound POWERNODE N331 is the easier recommendation: it leads on most of the measured areas and costs less. Take NAD C 700 if one of the "depends" rows above describes your system.
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.