These are not the same size of amplifier: NAD C 3050 has roughly 2x the power of NAD C 338. That is about 3dB, 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 | NAD C 3050 has more power - 100W against 50W into 8 ohms. That is about 3dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate NAD C 338 the better fit for desk or near-field listening and a small room, and NAD C 3050 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 barely increases (50W and 100W). |
| Noise floor | A | NAD C 338 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. |
| Streaming | B | Only NAD C 338 has Chromecast; 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 | B | 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 338 takes up about 18% less shelf area (1349cm² against 1638cm²), and it is 54mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | NAD C 338 costs less - $799 against $1,799 at list. |
A NAD C 338 B NAD C 3050
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 C 3050 measures better, NAD C 338 costs about 56% less. With most speakers in most rooms that gap is smaller in practice than it looks here. 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 3050 has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 50 watts is already more than most people ever use, and the extra 50 watts would be headroom you pay for and never hear - we rate NAD C 3050 poorly for near-field use for exactly that reason. Think about the whole system: the roughly $1,000 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.