These are not the same size of amplifier: HiFi Rose RS520 has roughly 2.5x the power of NAD M10 V3. That is about 4dB, 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 100W into 8 ohms. That is about 4dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output barely increases (100W and 250W). |
| Noise floor | B | HiFi Rose RS520 is the quieter design on paper - 109dB against 90dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | Both decode on board. HiFi Rose RS520 goes higher - 768kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only NAD M10 V3 has AirPlay 2 and BluOS. |
| Phono stage | depends | NAD M10 V3 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 | NAD M10 V3 is Class D and HiFi Rose RS520 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 | NAD M10 V3 takes up about 47% less shelf area (606cm² against 1135cm²), and it is 50mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | NAD M10 V3 costs less - $3,199 against $3,695 at list. |
| Watts per dollar | B | HiFi Rose RS520 is the cheaper watt - about $15 per watt against $32. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD M10 V3 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?
HiFi Rose RS520 leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. NAD M10 V3 is the one to take if it does not. 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, 100 watts is already more than most people ever use, and the extra 150 watts would be headroom you pay for and never hear - we rate HiFi Rose RS520 poorly for near-field use for exactly that reason. If you play records, NAD M10 V3 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.