These are not the same size of amplifier: HiFi Rose RA180 has roughly 2x the power of NAD Masters Series M33. That is about 3dB, 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 RA180 has more power - 400W against 200W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | A | NAD Masters Series M33 holds up better into a 4-ohm load: its output nearly doubles to 380W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | NAD Masters Series M33 is the quieter design on paper - 120dB against 107dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | NAD Masters Series M33 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Streaming | A | Only NAD Masters Series M33 has AirPlay 2, Roon and BluOS. |
| Analogue inputs | B | HiFi Rose RA180 takes more analogue sources - 4 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Headphones | depends | Only NAD Masters Series M33 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | NAD Masters Series M33 is Class D and HiFi Rose RA180 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. |
| Price | A | NAD Masters Series M33 costs less - $5,999 against $6,995 at list. |
| Watts per dollar | B | HiFi Rose RA180 is the cheaper watt - about $17 per watt against $30. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD Masters Series M33 B HiFi Rose RA180
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?
NAD Masters Series M33 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - NAD Masters Series M33 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 RA180 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 200 watts is already more than most people ever use, and the extra 200 watts would be headroom you pay for and never hear - we rate HiFi Rose RA180 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.