No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | A | Arcam A25+ has more power - 100W against 75W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases strongly (165W and 115W). |
| Noise floor | B | LEAK Stereo 230 is the quieter design on paper - 109dB against 106dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board. LEAK Stereo 230 goes higher - 768kHz against 384kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Analogue inputs | A | Arcam A25+ takes more analogue sources - 3 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Arcam A25+ is Class G and LEAK Stereo 230 is Class A/B. Class G/H switches its supply rails to cut the heat a Class A/B design wastes; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | B | LEAK Stereo 230 costs less - $1,695 against $2,000 at list. |
A Arcam A25+ B LEAK Stereo 230
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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it.
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.