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 | B | Arcam A25 has more power - 100W against 80W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate NAD C 700 the better fit for a small room, and Arcam A25 for a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | B | Arcam A25 holds up better into a 4-ohm load: its output increases strongly to 165W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | Arcam A25 is the quieter design on paper - 106dB against 84dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board. Arcam A25 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only NAD C 700 has AirPlay 2, Roon and BluOS. |
| Analogue inputs | B | Arcam A25 takes more analogue sources - 3 against 2. |
| Phono stage | depends | Arcam A25 has a built-in phono stage (MM) and NAD C 700 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. |
| Use with a TV | depends | Only NAD C 700 has HDMI eARC, 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 | A | Only NAD C 700 offers a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Headphones | depends | Only Arcam A25 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | NAD C 700 is Class D and Arcam A25 is Class G. Class D runs cool and draws almost nothing at idle; Class G/H switches its supply rails to cut the heat a Class A/B design wastes. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | NAD C 700 takes up about 59% less shelf area (651cm² against 1580cm²), and it is 68mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Arcam A25 costs less - $1,499 against $1,599 at list. |
| Watts per dollar | B | Arcam A25 is the cheaper watt - about $15 per watt against $20. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD C 700 B Arcam A25
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?
Arcam A25 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Arcam A25 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, Arcam A25 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.