These are not the same size of amplifier: Michi X3 Series 2 has roughly 2.9x the power of Naim Uniti Nova. That is about 4.7dB, 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 X3 Series 2 has more power - 235W against 80W into 8 ohms. That is about 4.7dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Michi X3 Series 2 the better fit for a large room and a very large room, and Naim Uniti Nova for desk or near-field listening, a small room and a mid-size room. Match the amplifier to the room you actually have, not the one you want. |
| Built-in DAC | A | Both decode on board, but only Michi X3 Series 2 handles MQA. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Analogue inputs | A | Michi X3 Series 2 takes more analogue sources - 5 against 2. |
| Phono stage | depends | Michi X3 Series 2 has a built-in phono stage (MM) and Naim Uniti Nova 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 Naim Uniti Nova 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. |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | Naim Uniti Nova takes up about 37% less shelf area (1371cm² against 2192cm²), and it is 136mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Naim Uniti Nova costs less - $6,899 against $7,499 at list. |
| Watts per dollar | A | Michi X3 Series 2 is the cheaper watt - about $32 per watt against $86. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Michi X3 Series 2 B Naim Uniti Nova
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?
Michi X3 Series 2 leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. Naim Uniti Nova is the one to take if it does not. 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 X3 Series 2 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 80 watts is already more than most people ever use, and the extra 155 watts would be headroom you pay for and never hear - we rate Michi X3 Series 2 poorly for near-field use for exactly that reason. If you play records, Michi X3 Series 2 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.