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 | Cambridge Audio Evo 150 has more power - 150W against 100W into 8 ohms. That is about 1.8dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Primare I25 Prisma the better fit for desk or near-field listening, a small room and a mid-size room, and Cambridge Audio Evo 150 for a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | A | Primare I25 Prisma holds up better into a 4-ohm load: its output nearly doubles to 200W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | A | Both decode on board. Primare I25 Prisma goes higher - 768kHz against 384kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Analogue inputs | A | Primare I25 Prisma takes more analogue sources - 5 against 2. |
| Phono stage | depends | Cambridge Audio Evo 150 has a built-in phono stage (MM) and Primare I25 Prisma does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Cambridge Audio Evo 150 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | Cambridge Audio Evo 150 takes up about 40% less shelf area (1190cm² against 1970cm²), and it is 84mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Cambridge Audio Evo 150 costs less - $3,249 against $4,495 at list. |
| Watts per dollar | B | Cambridge Audio Evo 150 is the cheaper watt - about $22 per watt against $45. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Primare I25 Prisma B Cambridge Audio Evo 150
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?
Primare I25 Prisma is ahead, but on only 1 of the measured areas, and it costs about 38% more. That is a lot of money for a narrow margin - Cambridge Audio Evo 150 is the sensible buy unless a specific feature above decides it for you. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Primare I25 Prisma is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, Cambridge Audio Evo 150 saves you buying a phono stage; if you do not, ignore that row entirely.
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.