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 | SVS Prime SoundBase has more power - 75W against 50W into 8 ohms. That is about 1.8dB, which is a small step in loudness but real headroom on peaks. |
| Room size | depends | We rate SVS Prime SoundBase 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. |
| Grip on hard loads | A | SVS Prime SoundBase holds up better into a 4-ohm load: its output nearly doubles to 150W, where the other barely increases. That matters with demanding speakers far more than the 8-ohm figure does. |
| Noise floor | B | NAD C 338 is the quieter design on paper - 98dB against 90dB. 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 SVS Prime SoundBase has AirPlay 2 and DTS Play-Fi. |
| 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 SVS Prime SoundBase 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 | SVS Prime SoundBase takes up about 62% less shelf area (517cm² against 1349cm²), and it is 86mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | A | SVS Prime SoundBase costs less - $699 against $799 at list. |
| Watts per dollar | A | SVS Prime SoundBase is the cheaper watt - about $9 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 SVS Prime SoundBase 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?
SVS Prime SoundBase is the easier recommendation: it leads on most of the measured areas and costs less. Take NAD C 338 if one of the "depends" rows above describes your system. If your speakers are a difficult load - 4 ohms nominal, big woofers, or a sensitivity in the low 80s - SVS Prime SoundBase 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 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.