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 - 50W against 60W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | A | Arcam A5+ holds up better into a 4-ohm load: its output increases strongly to 75W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | Marantz PM7000N is the quieter design on paper - 115dB against 106dB. 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 | B | Only Marantz PM7000N has AirPlay 2, Roon and HEOS. |
| Analogue inputs | evenly matched | The same number of line-level inputs (3). |
| Room to grow | B | Only Marantz PM7000N offers a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Price | A | Arcam A5+ costs less - $1,200 against $1,299 at list. |
A Arcam A5+ B Marantz PM7000N
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?
The usual trade-off: Marantz PM7000N measures better, Arcam A5+ costs about 8% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Arcam A5+ is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating.
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.