One is a streaming all-in-one and the other is an amplifier. Judge them on how many boxes you want and what you already own, not on the spec sheet alone.
| Area | Better | Why |
|---|
| Power | B | Marantz Stereo 70s has more power - 75W against 60W into 8 ohms. That is about 1dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate Technics SA-C600 the better fit for desk or near-field listening and a small room, and Marantz Stereo 70s for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Built-in DAC | B | Both decode on board, but only Marantz Stereo 70s handles DSD. |
| Streaming | evenly matched | Only Technics SA-C600 has Chromecast. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | B | Marantz Stereo 70s takes more analogue sources - 3 against 2. |
| Use with a TV | depends | Only Marantz Stereo 70s 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. |
| Built-in sources | depends | Technics SA-C600 has a CD player built in. That is one less box if you still play discs or listen to radio, and dead weight if you do not. |
| Amplifier class | depends | Technics SA-C600 is Class D and Marantz Stereo 70s 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. |
| Shelf space | depends | Technics SA-C600 takes up about 36% less shelf area (1161cm² against 1803cm²), and it is 67mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Marantz Stereo 70s costs less - $1,000 against $1,300 at list. |
| Watts per dollar | B | Marantz Stereo 70s is the cheaper watt - about $13 per watt against $22. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Technics SA-C600 B Marantz Stereo 70s
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?
Marantz Stereo 70s is the easier recommendation: it leads on most of the measured areas and costs less. Take Technics SA-C600 if one of the "depends" rows above describes your system. If this sits under a television, Marantz Stereo 70s is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
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.