These are not the same size of amplifier: Denon PMA-1700NE has roughly 2.3x the power of Technics SU-GX70. That is about 3.7dB, so it is a question of room size and how hard your speakers are to drive, not of one being the better amplifier.
| Area | Better | Why |
|---|
| Power | B | Denon PMA-1700NE has more power - 70W against 30W into 8 ohms. That is about 3.7dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Technics SU-GX70 the better fit for desk or near-field listening and a small room, and Denon PMA-1700NE for a mid-size room, a large room and a very large room. Match the amplifier to the room you actually have, not the one you want. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output nearly doubles (60W and 140W). |
| Built-in DAC | B | Both decode on board. Denon PMA-1700NE goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only Technics SU-GX70 has AirPlay 2 and Chromecast. |
| Analogue inputs | B | Denon PMA-1700NE takes more analogue sources - 3 against 2. |
| Room to grow | A | Only Technics SU-GX70 offers preamp outputs - which decides whether you can add a subwoofer or a power amplifier later without replacing the box. |
| Amplifier class | depends | Technics SU-GX70 is Class D and Denon PMA-1700NE 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. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | B | Denon PMA-1700NE is the cheaper watt - about $30 per watt against $67. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Technics SU-GX70 B Denon PMA-1700NE
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-1700NE has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. Start with the room. In a large or open-plan room, or with speakers that are hard to drive - low sensitivity, or an impedance that dips - Denon PMA-1700NE has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 30 watts is already more than most people ever use, and the extra 40 watts would be headroom you pay for and never hear - we rate Denon PMA-1700NE poorly for near-field use for exactly that reason.
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.