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 |
|---|
| Built-in DAC | A | Both decode on board, but only Marantz M-CR612 handles DSD. |
| Streaming | A | Only Marantz M-CR612 has AirPlay 2 and HEOS. |
| Phono stage | depends | NAD C 328 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. |
| 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. |
| Shelf space | depends | Marantz M-CR612 takes up about 37% less shelf area (849cm² against 1349cm²). |
| Price | A | Marantz M-CR612 costs less - $650 against $699 at list. |
A Marantz M-CR612 B NAD C 328
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 M-CR612 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If you play records, NAD C 328 saves you buying a phono stage; if you do not, ignore that row entirely.
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.