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 | Denon Home Amp 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. |
| Grip on hard loads | A | Cambridge CXA81 II holds up better into a 4-ohm load: its output increases strongly to 120W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | evenly matched | Only Cambridge CXA81 II has Roon; only Denon Home Amp has AirPlay 2 and HEOS. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Use with a TV | depends | Only Denon Home Amp has HDMI, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Cambridge CXA81 II is Class A/B and Denon Home Amp 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 | Denon Home Amp takes up about 64% less shelf area (580cm² against 1595cm²), and it is 104mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Denon Home Amp costs less - $899 against $1,199 at list. |
| Watts per dollar | B | Denon Home Amp is the cheaper watt - about $9 per watt against $15. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cambridge CXA81 II B Denon Home Amp
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?
Denon Home Amp has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Cambridge CXA81 II is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If this sits under a television, Denon Home Amp is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
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.