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 | SVS Prime SoundBase has more power - 75W against 45W into 8 ohms. That is about 2.2dB, so it plays usefully louder before it runs out and has more in hand on peaks. |
| Grip on hard loads | B | SVS Prime SoundBase holds up better into a 4-ohm load: its output nearly doubles to 150W, where the other increases modestly. That matters with demanding speakers far more than the 8-ohm figure does. |
| Built-in DAC | A | Both decode on board. MISSION 778X goes higher - 384kHz against 192kHz. Very few recordings exist above 192kHz, so treat this as headroom, not as sound quality. |
| Phono stage | depends | MISSION 778X 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. |
| Amplifier class | depends | MISSION 778X is Class A/B and SVS Prime SoundBase is Class D. Class A/B runs warm and is the long-established mainstream choice; Class D runs cool and draws almost nothing at idle. Modern examples of both measure well - judge by the rest of the page. |
| Price | A | MISSION 778X costs less - $549 against $699 at list. |
| Watts per dollar | B | SVS Prime SoundBase is the cheaper watt - about $9 per watt against $12. A blunt measure, and it says nothing about how either sounds, but it is the honest one for raw output. |
A MISSION 778X B SVS Prime SoundBase
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: SVS Prime SoundBase measures better, MISSION 778X costs about 21% less. With most speakers in most rooms that gap is smaller in practice than it looks here. 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. 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 - SVS Prime SoundBase has the headroom, and headroom is what stops an amplifier hardening up on peaks. At desk distance or in a small room, 45 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 SVS Prime SoundBase poorly for near-field use for exactly that reason.
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.