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 | A | NAD C 3050 has more power - 100W against 70W into 8 ohms. That is about 1.5dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate NAD C 3050 the better fit for a large room and a very large room, and Technics SU-G700M2 Grand Class for a small room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | B | Technics SU-G700M2 Grand Class holds up better into a 4-ohm load: its output nearly doubles to 140W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | B | Both decode on board. Technics SU-G700M2 Grand Class goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only NAD C 3050 has AirPlay 2, Roon and BluOS. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Room to grow | A | Only NAD C 3050 offers a pre-out/main-in loop - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Shelf space | depends | NAD C 3050 takes up about 21% less shelf area (1638cm² against 2069cm²), and it is 116mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | NAD C 3050 costs less - $2,449 against $2,700 at list. |
| Watts per dollar | A | NAD C 3050 is the cheaper watt - about $24 per watt against $39. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD C 3050 B Technics SU-G700M2 Grand Class
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?
NAD C 3050 has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Technics SU-G700M2 Grand Class is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating.
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.