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 | evenly matched | Effectively the same output - 185W against 200W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Amplifier class | depends | NAD C298 is Class D and Rotel RB-1582 MkII is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | B | Rotel RB-1582 MkII costs less - $2,499 against $3,099 at list. |
| Watts per dollar | B | Rotel RB-1582 MkII is the cheaper watt - about $12 per watt against $17. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD C298 B Rotel RB-1582 MkII
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?
Rotel RB-1582 MkII has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is.
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.