Siblings in Arcam's A range, so they share a design and a house sound. It comes down to power, features and price.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 100W against 100W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Room size | depends | We rate Arcam A25 the better fit for a large room and a very large room, and Arcam A25+ for a small room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases strongly (165W and 165W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (106dB vs 106dB). |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Analogue inputs | evenly matched | The same number of line-level inputs (3). |
| Use with a TV | depends | Only Arcam A25+ 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 | evenly matched | The same expansion options on both. |
| Price | A | Arcam A25 costs less - $1,499 against $2,000 at list. |
| Watts per dollar | A | 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 Arcam A25 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 this sits under a television, Arcam A25+ is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way. Think about the whole system: the roughly $501 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.