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 | B | HiFi Rose RA280 has more power - 250W against 150W into 8 ohms. That is about 2.2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | A | Buchardt I150 holds up better into a 4-ohm load: its output nearly doubles to 300W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | Buchardt I150 is the quieter design on paper - 121dB against 109dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Buchardt I150 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Phono stage | depends | HiFi Rose RA280 has a built-in phono stage and Buchardt I150 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 | A | Only Buchardt I150 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Buchardt I150 is Class D and HiFi Rose RA280 is Class AD. Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Buchardt I150 takes up about 30% less shelf area (1147cm² against 1638cm²), and it is 70mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Buchardt I150 costs less - $2,500 against $3,395 at list. |
A Buchardt I150 B HiFi Rose RA280
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?
Buchardt I150 is the easier recommendation: it leads on most of the measured areas and costs less. Take HiFi Rose RA280 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 - Buchardt I150 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - HiFi Rose RA280 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 150 watts is already more than most people ever use, and the extra 100 watts would be headroom you pay for and never hear.
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.