These sit in different price classes - KEF LSX II LT costs roughly 1.7x what ELAC Debut DCB41 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 | A | KEF LSX II LT digs deeper - 54Hz against 66Hz. |
| Built-in power | A | KEF LSX II LT has the bigger amplifier (200W vs 100W RMS). |
| Connections | A | KEF LSX II LT adds Wi-Fi and streaming. |
| Size | depends | KEF LSX II LT is easier to place; ELAC Debut DCB41 is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | depends | KEF LSX II LT: a sub output; ELAC Debut DCB41: a sub output. KEF LSX II LT sits in a wider range (10 models), so a matched surround system is easier later. |
| Price | B | ELAC Debut DCB41 is cheaper - $599 against $999, about 40% less; arguably a different class. |
A KEF LSX II LT B ELAC Debut DCB41
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?
The usual trade-off: KEF LSX II LT measures better, ELAC Debut DCB41 costs about about 67% more% less. Whether that gap is worth the money is the call only you can make - and in a normal room it is often smaller than the numbers suggest. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 66Hz anyway, which makes the cheaper ELAC Debut DCB41 much easier to justify. Think about the whole system, not just the speakers: the roughly $400 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.