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 | A | Marantz Cinema 50 has more power - 110W against 80W into 8 ohms. That is about 1.4dB, which is a small step in loudness but real headroom on peaks. |
| Speaker load rating | A | Marantz Cinema 50 is rated down to 4 ohms against 8, so it is the safer partner for a low-impedance speaker. |
| Analogue inputs | B | ARCAM AVR11 takes more analogue sources - 6 against 5. |
| Phono stage | depends | Marantz Cinema 50 has a built-in phono stage and ARCAM AVR11 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. |
| Shelf space | depends | Marantz Cinema 50 takes up about 14% less shelf area (1759cm² against 2043cm²), and it is 73mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Marantz Cinema 50 costs less - $2,800 against $3,050 at list. |
| Watts per dollar | A | Marantz Cinema 50 is the cheaper watt - about $25 per watt against $38. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Marantz Cinema 50 B ARCAM AVR11
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?
Marantz Cinema 50 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, Marantz Cinema 50 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.