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 CXA81 II has more power - 80W against 35W into 8 ohms. That is about 3.6dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Cayin Jazz 70 the better fit for desk or near-field listening and a small room, and Cambridge CXA81 II 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. |
| Grip on hard loads | B | Cambridge CXA81 II holds up better into a 4-ohm load: its output increases strongly to 120W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | Cambridge CXA81 II is the quieter design on paper - 105dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board, but only Cambridge CXA81 II handles DSD. |
| Analogue inputs | B | Cambridge CXA81 II takes more analogue sources - 5 against 3. |
| Amplifier type | depends | Cayin Jazz 70 is Tube and Cambridge CXA81 II 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. |
| Shelf space | depends | Cayin Jazz 70 takes up about 36% less shelf area (1014cm² against 1595cm²), and it is 32mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Cambridge CXA81 II costs less - $1,199 against $1,399 at list. |
| Watts per dollar | B | Cambridge CXA81 II is the cheaper watt - about $15 per watt against $40. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cayin Jazz 70 B Cambridge CXA81 II
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 CXA81 II is the easier recommendation: it leads on most of the measured areas and costs less. Take Cayin Jazz 70 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 CXA81 II 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 CXA81 II has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 35 watts is already more than most people ever use, and the extra 45 watts would be headroom you pay for and never hear - we rate Cambridge CXA81 II poorly for near-field use for exactly that reason.
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.