A floor-standing against a bookshelf. They are built for different places in a room, so start with where these have to go rather than which looks better on paper.
| Area | Better | Why |
|---|
| Bass | A | Q Acoustics M40 digs deeper - 38Hz against 45Hz. A subwoofer would even that out. |
| Built-in power | B | KEF LS50 Wireless II has the bigger amplifier (380W vs 50W RMS). |
| Connections | B | KEF LS50 Wireless II adds Wi-Fi and HDMI. |
| Size | depends | KEF LS50 Wireless II is easier to place; Q Acoustics M40 is bigger, which usually goes with fuller bass. Your room decides. |
| Type | depends | A Powered Floor-standing against a Powered Bookshelf - a different job rather than a better one. |
| Expandability | depends | Q Acoustics M40: a sub output; KEF LS50 Wireless II: a sub output. |
| Price | A | Q Acoustics M40 is cheaper - $999 against $2,999, about 67% less; arguably a different class. |
A Q Acoustics M40 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 ahead, but only on 1 of the measured areas, and it costs about 3x the price. That is a lot of money for a narrow margin on paper - Q Acoustics M40 looks like the sensible buy unless something else about the KEF LS50 Wireless II appeals to you. If a subwoofer is in your plans, the bass gap largely stops mattering - you would be crossing over above 45Hz anyway, so judge these on the other rows instead. In a large or open-plan room, Q Acoustics M40 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, KEF LS50 Wireless II 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.