No single best amplifier here. What decides it is what you have to drive, what you need to plug in, and how much of the system you want in one box.
| Area | Better | Why |
|---|
| Power | A | Bluesound POWERNODE has more power - 80W against 50W into 8 ohms. That is about 2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Room size | depends | We rate Bluesound POWERNODE the better fit for a mid-size room, a large room and a very large room, and NAD C 338 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 | evenly matched | Much the same signal-to-noise ratio (100dB vs 98dB). |
| Built-in DAC | A | Both decode on board. Bluesound POWERNODE goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Streaming | A | Only Bluesound POWERNODE has AirPlay 2, Roon and BluOS; only NAD C 338 has Chromecast. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Phono stage | depends | NAD C 338 has a built-in phono stage (MM) and Bluesound POWERNODE does not. Decisive if you own a turntable, completely irrelevant if you do not - and an outboard phono stage is easy to add later either way. |
| Room to grow | evenly matched | The same expansion options on both. |
| Shelf space | depends | Bluesound POWERNODE takes up about 69% less shelf area (420cm² against 1349cm²), and it is 120mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | NAD C 338 costs less - $799 against $949 at list. |
| Watts per dollar | A | Bluesound POWERNODE is the cheaper watt - about $12 per watt against $16. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A Bluesound POWERNODE 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?
Bluesound POWERNODE leads across most of the measured areas for a fairly modest premium, so it is the easier pick if the budget stretches. NAD C 338 is the one to take if it does not. 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 - Bluesound POWERNODE 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 30 watts would be headroom you pay for and never hear - we rate Bluesound POWERNODE poorly for near-field use for exactly that reason. If you play records, NAD C 338 saves you buying a phono stage; if you do not, ignore that row entirely.
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.