These are not the same size of amplifier: Anthem STR has roughly 2.9x the power of Marantz Model 40n. That is about 4.6dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | A | Anthem STR has more power - 200W against 70W into 8 ohms. That is about 4.6dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Anthem STR the better fit for a large room and a very large room, and Marantz Model 40n for desk or near-field listening, a small room and a mid-size room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | A | Anthem STR holds up better into a 4-ohm load: its output nearly doubles to 400W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | Anthem STR is the quieter design on paper - 120dB against 106dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board, but only Anthem STR handles DSD. |
| Streaming | B | Only Marantz Model 40n has AirPlay 2, Roon and HEOS. |
| Analogue inputs | A | Anthem STR takes more analogue sources - 5 against 3. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Marantz Model 40n has a headphone output. Worth something if you listen late, nothing if you never do. |
| Price | B | Marantz Model 40n costs less - $2,499 against $5,000 at list. |
| Watts per dollar | A | Anthem STR is the cheaper watt - about $25 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 Anthem STR B Marantz Model 40n
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: Anthem STR measures better, Marantz Model 40n costs about 50% 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 - Anthem STR is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - Anthem STR has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 70 watts is already more than most people ever use, and the extra 130 watts would be headroom you pay for and never hear - we rate Anthem STR poorly for near-field use for exactly that reason.
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.