One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 70W against 70W 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 modestly (100W and 100W). |
| Noise floor | B | Marantz Model 50 is the quieter design on paper - 113dB against 106dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Marantz Model 40n has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Streaming | A | Only Marantz Model 40n has AirPlay 2, Roon and HEOS. |
| Analogue inputs | B | Marantz Model 50 takes more analogue sources - 5 against 3. |
| Use with a TV | depends | Only Marantz Model 40n has HDMI ARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | B | Marantz Model 50 costs less - $1,800 against $2,499 at list. |
| Watts per dollar | B | Marantz Model 50 is the cheaper watt - about $26 per watt against $36. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Marantz Model 40n B Marantz Model 50
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 Model 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 this sits under a television, Marantz Model 40n is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Marantz Model 50 becomes the more rational buy.
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.