Different price classes - Marantz PM6007 costs roughly 1.8x what Denon PMA-600NE does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Power | evenly matched | Effectively the same output - 45W against 45W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Noise floor | A | Denon PMA-600NE is the quieter design on paper - 105dB against 102dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | evenly matched | Both have a DAC on board with much the same capability. |
| Analogue inputs | evenly matched | The same number of line-level inputs (4). |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | Denon PMA-600NE takes up about 20% less shelf area (1405cm² against 1764cm²), and it is 76mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | Denon PMA-600NE costs less - $499 against $899 at list. |
| Watts per dollar | A | Denon PMA-600NE is the cheaper watt - about $11 per watt against $20. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Denon PMA-600NE B Marantz PM6007
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?
Denon PMA-600NE is the easier recommendation: it leads on most of the measured areas and costs less. Take Marantz PM6007 if one of the "depends" rows above describes your system. Think about the whole system: the roughly $400 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
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.