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 | evenly matched | Effectively the same output - 60W against 50W into 8 ohms is under 1dB, which is not an audible difference in loudness. |
| Noise floor | evenly matched | Much the same signal-to-noise ratio (98dB vs 98dB). |
| Built-in DAC | A | Both decode on board. NAD D 3045 goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | evenly matched | Only NAD C 338 has Chromecast. Neither list is longer in a way that matters - check the one service you actually pay for. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | NAD D 3045 takes up about 85% less shelf area (208cm² against 1349cm²), and it is 21mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | NAD C 338 costs less - $799 against $899 at list. |
A NAD D 3045 B NAD C 338
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?
The usual trade-off: NAD D 3045 measures better, NAD C 338 costs about 11% less. With most speakers in most rooms that gap is smaller in practice than it looks here.
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.