Both are Marantz, from different ranges - the engineering approach is shared and the differences are mostly in power, connectivity and price.
| Area | Better | Why |
|---|
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Streaming | evenly matched | The same streaming platforms and services on both. |
| Phono stage | depends | Marantz Stereo 70s has a built-in phono stage (MM) and Marantz M-CR612 does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| 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 | Marantz M-CR612 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 | Marantz M-CR612 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 | Marantz M-CR612 takes up about 53% less shelf area (849cm² against 1803cm²), and it is 106mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Marantz M-CR612 costs less - $650 against $1,000 at list. |
A Marantz M-CR612 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?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it. If you play records, Marantz Stereo 70s saves you buying a phono stage; if you do not, ignore that row entirely. 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.