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 | Denon Home Amp 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. |
| Grip on hard loads | A | Arcam A15 holds up better into a 4-ohm load: its output increases strongly to 120W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | B | Both decode on board, but only Denon Home Amp handles DSD. |
| Streaming | B | Only Denon Home Amp has AirPlay 2 and HEOS. |
| Phono stage | depends | Arcam A15 has a built-in phono stage (MM) and Denon Home Amp 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 Denon Home Amp has HDMI, 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 | B | Only Denon Home Amp offers a subwoofer output - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Arcam A15 is Class A/B and Denon Home Amp is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Denon Home Amp takes up about 63% less shelf area (580cm² against 1580cm²), and it is 98mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Denon Home Amp costs less - $899 against $999 at list. |
| Watts per dollar | B | Denon Home Amp is the cheaper watt - about $9 per watt against $12. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Arcam A15 B Denon Home Amp
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?
Denon Home Amp is the easier recommendation: it leads on most of the measured areas and costs less. Take Arcam A15 if one of the "depends" rows above describes your system. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Arcam A15 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 A15 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.