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 - 100W against 100W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | B | Marantz Model 30 holds up better into a 4-ohm load: its output nearly doubles to 200W, where the other increases strongly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | A | Audiolab 9000A is the quieter design on paper - 110dB against 88dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | Audiolab 9000A has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | B | Marantz Model 30 takes more analogue sources - 6 against 3. |
| Room to grow | A | Only Audiolab 9000A offers a pre-out/main-in loop - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Audiolab 9000A is Class A/B and Marantz Model 30 is Class D. Class A/B runs warm and is the long-established mainstream choice; 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 | Audiolab 9000A takes up about 25% less shelf area (1518cm² against 2033cm²), and it is 117mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | evenly matched | Priced within a few per cent of each other. |
A Audiolab 9000A B Marantz Model 30
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?
Audiolab 9000A 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 - Marantz Model 30 is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Marantz Model 30 becomes the more rational buy.
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.