Different price classes - Naim Nova PE costs roughly 1.8x what Arcam SA45 does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 180W against 150W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases strongly (300W and 250W). |
| Built-in DAC | B | Both decode on board, but only Naim Nova PE handles DSD. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Phono stage | depends | Arcam SA45 has a built-in phono stage and Naim Nova PE 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. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Naim Nova PE has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Arcam SA45 is Class G and Naim Nova PE is Class D. Class G/H switches its supply rails to cut the heat a Class A/B design wastes; 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 | Naim Nova PE takes up about 36% less shelf area (1145cm² against 1796cm²), and it is 149mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Arcam SA45 costs less - $5,500 against $9,999 at list. |
| Watts per dollar | A | Arcam SA45 is the cheaper watt - about $31 per watt against $67. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Arcam SA45 B Naim Nova PE
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. If you play records, Arcam SA45 saves you buying a phono stage; if you do not, ignore that row entirely. Think about the whole system: the roughly $4,499 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.