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 | evenly matched | Effectively the same output - 250W against 250W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output barely increases (250W and 250W). |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (109dB vs 109dB). |
| Built-in DAC | B | HiFi Rose RS520 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 HiFi Rose RS520 has Roon. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Phono stage | depends | HiFi Rose RA280 has a built-in phono stage 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. |
| Room to grow | B | Only HiFi Rose RS520 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Shelf space | depends | HiFi Rose RS520 takes up about 31% less shelf area (1135cm² against 1638cm²), and it is 52mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | HiFi Rose RA280 costs less - $3,395 against $3,695 at list. |
A HiFi Rose RA280 B HiFi Rose RS520
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?
The usual trade-off: HiFi Rose RS520 measures better, HiFi Rose RA280 costs about 8% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If you play records, HiFi Rose RA280 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 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.