A generation apart: SVS Prime Wireless Pro is the newer design, against a 2018 model. Newer is not automatically better, but the older one is more likely to be discounted or near run-out.
| Area | Better | Why |
|---|
| Bass | A | SVS Prime Wireless Pro digs deeper - 42Hz against 59Hz. |
| Built-in power | evenly matched | Similar onboard amplification (200W vs 200W RMS). |
| Connections | A | SVS Prime Wireless Pro adds HDMI. |
| Size | depends | KEF LSX is easier to place; SVS Prime Wireless Pro is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | SVS Prime Wireless Pro: a sub output; KEF LSX: a sub output. |
| Price | A | SVS Prime Wireless Pro is cheaper - $899 against $1,250, about 28% less. |
A SVS Prime Wireless Pro B KEF LSX
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 speakers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
SVS Prime Wireless Pro is the easier recommendation: it leads on most of the measured areas and costs less. Take KEF LSX if its size, looks or fit in your room suit you better. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 59Hz anyway, so judge these on the other rows instead. In a large or open-plan room, SVS Prime Wireless Pro has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, KEF LSX is the easier speaker to get right.
And remember what a spec sheet cannot show: how each looks in your room and whether the finish suits it, what dealer support and warranty are like where you live, and how they actually sound to you. If you can hear them first - ideally with your own music - that will tell you more than any number above.