These are not the same size of amplifier: Michi S5 has roughly 3.9x the power of Naim Nova PE. That is about 5.9dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | A | Michi S5 has more power - 580W against 150W into 8 ohms. That is about 5.9dB - a different class of amplifier rather than a bigger version of the same one, and far more than most rooms will ever ask for. |
| Grip on hard loads | B | Naim Nova PE holds up better into a 4-ohm load: its output increases strongly to 250W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | B | Naim Nova PE has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Use with a TV | depends | Only Naim Nova PE has HDMI ARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Headphones | depends | Only Naim Nova PE has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Michi S5 is Class A/B and Naim Nova PE 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 | Naim Nova PE takes up about 49% less shelf area (1145cm² against 2255cm²), and it is 200mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Michi S5 costs less - $9,499 against $9,999 at list. |
| Watts per dollar | A | Michi S5 is the cheaper watt - about $16 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 Michi S5 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 your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Naim Nova PE is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - Michi S5 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 150 watts is already more than most people ever use, and the extra 430 watts would be headroom you pay for and never hear - we rate Michi S5 poorly for near-field use for exactly that reason.
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.