A valve amplifier against a solid-state one. They are not really rivals: they differ in character, in what they will drive and in what owning them involves, so start there rather than with the watts.
| Area | Better | Why |
|---|
| Power | B | Cambridge Audio MXW70 has more power - 70W against 28W into 8 ohms. That is about 4dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | B | Cambridge Audio MXW70 holds up better into a 4-ohm load: its output increases strongly to 125W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Analogue inputs | A | FiiO EA13 takes more analogue sources - 4 against 2. |
| Amplifier type | depends | FiiO EA13 is Tube and Cambridge Audio MXW70 is Solid State. Valve designs are usually warmer and softer at the limits and need their tubes replaced eventually; solid state is the lower-maintenance choice. This is a taste and ownership decision, not a quality one. |
| Price | B | Cambridge Audio MXW70 costs less - $599 against $770 at list. |
| Watts per dollar | B | Cambridge Audio MXW70 is the cheaper watt - about $9 per watt against $28. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A FiiO EA13 B Cambridge Audio MXW70
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?
Cambridge Audio MXW70 is the easier recommendation: it leads on most of the measured areas and costs less. Take FiiO EA13 if one of the "depends" rows above describes your system. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Cambridge Audio MXW70 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. 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 - Cambridge Audio MXW70 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 28 watts is already more than most people ever use, and the extra 42 watts would be headroom you pay for and never hear.
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.