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 - 70W against 75W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output increases modestly (100W and 115W). |
| Noise floor | A | Marantz Model 50 is the quieter design on paper - 113dB against 109dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | B | LEAK Stereo 230 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | A | Marantz Model 50 takes more analogue sources - 5 against 2. |
| Use with a TV | depends | Only LEAK Stereo 230 has HDMI ARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | LEAK Stereo 230 takes up about 27% less shelf area (1454cm² against 2002cm²). |
| Price | B | LEAK Stereo 230 costs less - $1,695 against $1,800 at list. |
A Marantz Model 50 B LEAK Stereo 230
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: Marantz Model 50 measures better, LEAK Stereo 230 costs about 6% less. With most speakers in most rooms that gap is smaller in practice than it looks here. If this sits under a television, LEAK Stereo 230 is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Marantz Model 50 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.