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 | A | HiFi Rose RA280 has more power - 250W against 200W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Grip on hard loads | B | Rotel Diamond RA-6000 holds up better into a 4-ohm load: its output increases strongly to 350W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | HiFi Rose RA280 is the quieter design on paper - 109dB against 103dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Rotel Diamond RA-6000 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 Diamond RA-6000 has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Room to grow | B | Only Rotel Diamond RA-6000 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Headphones | depends | Only Rotel Diamond RA-6000 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | HiFi Rose RA280 is Class AD and Rotel Diamond RA-6000 is Class A/B. 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. |
| Shelf space | depends | HiFi Rose RA280 takes up about 17% less shelf area (1638cm² against 1979cm²), and it is 76mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | HiFi Rose RA280 costs less - $3,395 against $4,500 at list. |
| Watts per dollar | A | HiFi Rose RA280 is the cheaper watt - about $14 per watt against $23. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A HiFi Rose RA280 B Rotel Diamond RA-6000
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 - Rotel Diamond RA-6000 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and HiFi Rose RA280 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.