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 | A | Sony ES STR-AZ1000ES has more power - 70W against 50W into 8 ohms. That is about 1.5dB, which is a small step in loudness but real headroom on peaks. |
| Speaker load rating | B | Marantz Cinema 70s Series 2 is rated down to 4 ohms against 6, so it is the safer partner for a low-impedance speaker. |
| Analogue inputs | evenly matched | The same number of line-level inputs (3). |
| Phono stage | depends | Marantz Cinema 70s Series 2 has a built-in phono stage and Sony ES STR-AZ1000ES 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 | B | Only Marantz Cinema 70s Series 2 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Price | A | Sony ES STR-AZ1000ES costs less - $1,398 against $1,500 at list. |
| Watts per dollar | A | Sony ES STR-AZ1000ES is the cheaper watt - about $20 per watt against $30. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Sony ES STR-AZ1000ES B Marantz Cinema 70s Series 2
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 Cinema 70s Series 2 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.