A valve amplifier against a solid-state one. They are not really rivals: they differ in character, in what they will drive and in what owning them involves, so start there rather than with the watts.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 40W against 40W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Built-in DAC | B | Naim Uniti Atom 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 (1). |
| Use with a TV | depends | Only Naim Uniti Atom 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 Uniti Atom has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier type | depends | PrimaLuna EVO 100 Power is Tube and Naim Uniti Atom is Solid State. Valve designs are usually warmer and softer at the limits and need their tubes replaced eventually; solid state is the lower-maintenance choice. This is a taste and ownership decision, not a quality one. |
| Shelf space | depends | Naim Uniti Atom takes up about 31% less shelf area (781cm² against 1128cm²), and it is 88mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | PrimaLuna EVO 100 Power costs less - $3,095 against $3,799 at list. |
A PrimaLuna EVO 100 Power B Naim Uniti Atom
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?
The usual trade-off: Naim Uniti Atom measures better, PrimaLuna EVO 100 Power costs about 19% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If this sits under a television, Naim Uniti Atom is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and PrimaLuna EVO 100 Power becomes the more rational buy.
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.