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 | B | Schiit Wotan has more power - 200W against 150W into 8 ohms. That is about 1.2dB, which is a small step in loudness but real headroom on peaks. |
| Grip on hard loads | B | Schiit Wotan holds up better into a 4-ohm load: its output nearly doubles to 400W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | Schiit Wotan is the quieter design on paper - 124dB against 95dB. Audible mainly with sensitive speakers in a quiet room. |
| Built-in DAC | A | NAD C 388 BluOS-2i has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Phono stage | depends | NAD C 388 BluOS-2i has a built-in phono stage (MM) and Schiit Wotan 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. |
| Headphones | depends | Only NAD C 388 BluOS-2i has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | NAD C 388 BluOS-2i is Class D and Schiit Wotan is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Shelf space | depends | Schiit Wotan takes up about 27% less shelf area (1342cm² against 1840cm²), and it is 93mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | evenly matched | Priced within a few per cent of each other. |
| Watts per dollar | B | Schiit Wotan is the cheaper watt - about $10 per watt against $13. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A NAD C 388 BluOS-2i B Schiit Wotan
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?
Schiit Wotan has the edge on paper, though not by much. The rows marked "depends" are more likely to decide this than the score is. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - Schiit Wotan is the safer partner, because how an amplifier behaves when the impedance drops matters more than its 8-ohm rating. If you play records, NAD C 388 BluOS-2i 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.