Different price classes - Esoteric F-02 costs roughly 1.8x what Rega Osiris 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 | B | Rega Osiris has more power - 160W against 120W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Esoteric F-02 the better fit for desk or near-field listening, a small room and a mid-size room, and Rega Osiris for a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | A | Esoteric F-02 holds up better into a 4-ohm load: its output nearly doubles to 240W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Analogue inputs | A | Esoteric F-02 takes more analogue sources - 7 against 5. |
| Phono stage | depends | Esoteric F-02 has a built-in phono stage (MM and MC) and Rega Osiris 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. |
| Headphones | depends | Only Esoteric F-02 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Shelf space | depends | Rega Osiris takes up about 28% less shelf area (1519cm² against 2096cm²), and it is 121mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Rega Osiris costs less - $11,600 against $21,000 at list. |
| Watts per dollar | B | Rega Osiris is the cheaper watt - about $73 per watt against $175. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Esoteric F-02 B Rega Osiris
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 - Esoteric F-02 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, Esoteric F-02 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.