Different price classes - Rega Osiris costs roughly 3.5x what Rega Elicit MK5 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 | A | Rega Osiris has more power - 160W against 105W into 8 ohms. That is about 1.8dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Rega Osiris the better fit for a very large room, and Rega Elicit MK5 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. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases strongly (250W and 162W). |
| Built-in DAC | B | Rega Elicit MK5 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Rega Osiris takes more analogue sources - 5 against 4. |
| Phono stage | depends | Rega Elicit MK5 has a built-in phono stage (MM) 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 Rega Elicit MK5 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Price | B | Rega Elicit MK5 costs less - $3,345 against $11,600 at list. |
| Watts per dollar | B | Rega Elicit MK5 is the cheaper watt - about $32 per watt against $73. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Rega Osiris B Rega Elicit MK5
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, Rega Elicit MK5 saves you buying a phono stage; if you do not, ignore that row entirely. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Rega Osiris 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.