These are not the same size of amplifier: NAD C 389 has roughly 2.2x the power of NAD D 3045. That is about 3.4dB, 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 | A | NAD C 389 has more power - 130W against 60W into 8 ohms. That is about 3.4dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate NAD C 389 the better fit for a mid-size room, a large room and a very large room, and NAD D 3045 for desk or near-field listening and a small room. Match the amplifier to the room you actually have, not the one you want. |
| Noise floor | B | NAD D 3045 is the quieter design on paper - 98dB against 95dB. 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 | A | NAD C 389 takes more analogue sources - 3 against 2. |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | NAD D 3045 takes up about 88% less shelf area (208cm² against 1705cm²), and it is 103mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | NAD D 3045 costs less - $899 against $1,999 at list. |
A NAD C 389 B NAD D 3045
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 389 is ahead, but on only 1 of the measured areas, and it costs about 122% more. That is a lot of money for a narrow margin - NAD D 3045 is the sensible buy unless a specific feature above decides it for you. 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 - NAD C 389 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 60 watts is already more than most people ever use, and the extra 70 watts would be headroom you pay for and never hear - we rate NAD C 389 poorly for near-field use for exactly that reason. Think about the whole system: the roughly $1,100 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.