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 | evenly matched | Effectively the same output - 100W against 120W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases strongly (155W and 200W). |
| Noise floor | B | Rotel RA-1572 MKII is the quieter design on paper - 100dB against 91dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Analogue inputs | A | Cambridge EXA100 takes more analogue sources - 5 against 4. |
| Phono stage | depends | Rotel RA-1572 MKII has a built-in phono stage (MM) and Cambridge EXA100 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. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | B | Rotel RA-1572 MKII is the cheaper watt - about $18 per watt against $22. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Cambridge EXA100 B Rotel RA-1572 MKII
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?
Rotel RA-1572 MKII has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, Rotel RA-1572 MKII 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.