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 389 BluOS-D has more power - 130W against 80W into 8 ohms. That is about 2.1dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | evenly matched | Both behave much the same into 4 ohms - output barely increases (130W and 80W). |
| Noise floor | B | NAD C 368 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 | A | Only NAD C 389 BluOS-D has AirPlay 2, Roon and BluOS. |
| Use with a TV | depends | Only NAD C 389 BluOS-D has HDMI eARC, so the television can drive it directly and one remote controls the volume. If the system is for music only, this changes nothing. |
| Room to grow | evenly matched | The same expansion options on both. |
| Price | B | NAD C 368 costs less - $1,499 against $2,549 at list. |
A NAD C 389 BluOS-D B NAD C 368
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 BluOS-D is ahead, but on only 1 of the measured areas, and it costs about 70% more. That is a lot of money for a narrow margin - NAD C 368 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 BluOS-D has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 80 watts is already more than most people ever use, and the extra 50 watts would be headroom you pay for and never hear. If this sits under a television, NAD C 389 BluOS-D is the one to buy - HDMI ARC means the TV remote controls the volume and there is no second box in the way.
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.