One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | B | Rotel RA-1592 MKII has more power - 200W against 150W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Grip on hard loads | A | Primare I35 holds up better into a 4-ohm load: its output nearly doubles to 300W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | Rotel RA-1592 MKII is the quieter design on paper - 103dB against 100dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Rotel RA-1592 MKII has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Streaming | evenly matched | Only Rotel RA-1592 MKII has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | A | Primare I35 takes more analogue sources - 5 against 4. |
| Phono stage | depends | Rotel RA-1592 MKII has a built-in phono stage (MM) and Primare I35 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. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only Rotel RA-1592 MKII has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Primare I35 is Class D and Rotel RA-1592 MKII is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | B | Rotel RA-1592 MKII costs less - $3,200 against $4,595 at list. |
| Watts per dollar | B | Rotel RA-1592 MKII is the cheaper watt - about $16 per watt against $31. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Primare I35 B Rotel RA-1592 MKII
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?
Rotel RA-1592 MKII is the easier recommendation: it leads on most of the measured areas and costs less. Take Primare I35 if one of the "depends" rows above describes your system. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Primare I35 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, Rotel RA-1592 MKII 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.