These are not the same size of amplifier: FiiO AIR AMP has roughly 3.6x the power of Cambridge Audio AXA25. That is about 5.6dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | FiiO AIR AMP has more power - 90W against 25W into 8 ohms. That is about 5.6dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Room size | depends | We rate Cambridge Audio AXA25 the better fit for desk or near-field listening and a small room, and FiiO AIR AMP for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Speaker load rating | B | FiiO AIR AMP is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| Built-in DAC | B | FiiO AIR AMP has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Streaming | evenly matched | Only FiiO AIR AMP has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | A | Cambridge Audio AXA25 takes more analogue sources - 5 against 1. |
| Room to grow | B | Only FiiO AIR AMP offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Cambridge Audio AXA25 is Class A/B and FiiO AIR 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. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | B | FiiO AIR AMP is the cheaper watt - about $3 per watt against $12. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cambridge Audio AXA25 B FiiO AIR 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?
FiiO AIR AMP has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - FiiO AIR AMP has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 25 watts is already more than most people ever use, and the extra 65 watts would be headroom you pay for and never hear - we rate FiiO AIR AMP poorly for near-field use for exactly that reason. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Cambridge Audio AXA25 becomes the more rational buy.
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.