These are not the same size of amplifier: HiFi Rose RS520 has roughly 2.1x the power of Arcam SA35. That is about 3.2dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | HiFi Rose RS520 has more power - 250W against 120W into 8 ohms. That is about 3.2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | A | Arcam SA35 holds up better into a 4-ohm load: its output increases strongly to 200W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (110dB vs 109dB). |
| Built-in DAC | B | 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 | A | Only Arcam SA35 has AirPlay 2 and Chromecast. |
| Phono stage | depends | Arcam SA35 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 | evenly matched | The same expansion options on both. |
| Amplifier class | depends | Arcam SA35 is Class G and HiFi Rose RS520 is Class AD. Class G/H switches its supply rails to cut the heat a Class A/B design wastes. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | HiFi Rose RS520 takes up about 28% less shelf area (1135cm² against 1575cm²), and it is 36mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Arcam SA35 costs less - $3,300 against $3,695 at list. |
| Watts per dollar | B | HiFi Rose RS520 is the cheaper watt - about $15 per watt against $28. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Arcam SA35 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, Arcam SA35 costs about 11% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Arcam SA35 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 RS520 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 120 watts is already more than most people ever use, and the extra 130 watts would be headroom you pay for and never hear - we rate HiFi Rose RS520 poorly for near-field use for exactly that reason.
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.