No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 250W against 235W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | B | Rotel Diamond RA-6000 holds up better into a 4-ohm load: its output increases modestly 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 RS520 is the quieter design on paper - 109dB against 103dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Both decode on board. HiFi Rose RS520 goes higher - 768kHz against 384kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Analogue inputs | B | Rotel Diamond RA-6000 takes more analogue sources - 4 against 1. |
| Phono stage | depends | Rotel Diamond RA-6000 has a built-in phono stage (MM) and HiFi Rose RS520 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. |
| Use with a TV | depends | Only HiFi Rose RS520 has HDMI eARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Room to grow | B | Only Rotel Diamond RA-6000 offers A/B speaker terminals - 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 RS520 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 RS520 takes up about 43% less shelf area (1135cm² against 1979cm²), and it is 128mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | HiFi Rose RS520 costs less - $3,695 against $4,499 at list. |
| Watts per dollar | A | HiFi Rose RS520 is the cheaper watt - about $15 per watt against $19. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A HiFi Rose RS520 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 play records, Rotel Diamond RA-6000 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.