These sit in different price classes - Sony Signature Series SA-Z1 costs roughly 2.7x what KEF LS50 Wireless II does. Expect it to lead on paper; the question is whether the gap is audible enough in your room to be worth it.
| Area | Better | Why |
|---|
| Bass | B | KEF LS50 Wireless II digs deeper - 45Hz against 51Hz. A subwoofer would even that out. |
| Built-in power | B | KEF LS50 Wireless II has the bigger amplifier (380W vs 212W RMS). |
| Connections | B | KEF LS50 Wireless II adds Bluetooth, Wi-Fi, streaming and HDMI. |
| Size | depends | Sony Signature Series SA-Z1 is easier to place; KEF LS50 Wireless II is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | B | KEF LS50 Wireless II: a sub output. |
| Price | B | KEF LS50 Wireless II is cheaper - $2,999 against $8,000, about 63% less; arguably a different class. |
A Sony Signature Series SA-Z1 B KEF LS50 Wireless II
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?
KEF LS50 Wireless II is the easier recommendation: it leads on most of the measured areas and costs less. Take Sony Signature Series SA-Z1 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 51Hz anyway, so judge these on the other rows instead. Think about the whole system, not just the speakers: the roughly $5,001 saved by taking the cheaper pair would buy a subwoofer or a better amplifier, and either usually does more for the sound than the difference between these two.
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.