One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| 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 | B | Cambridge Audio CXA81 is the quieter design on paper - 105dB against 102dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board. Cambridge Audio CXA81 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only Bluesound POWERNODE N331 has AirPlay 2, Roon and BluOS. |
| Analogue inputs | B | Cambridge Audio CXA81 takes more analogue sources - 5 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Bluesound POWERNODE N331 is Class D and Cambridge Audio CXA81 is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Bluesound POWERNODE N331 takes up about 74% less shelf area (418cm² against 1595cm²), and it is 180mm 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 Cambridge Audio CXA81
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.