Different kinds of product: one is active with its amplifier built in, the other passive and needs one. Judge them on how you want to own the system, not just the specs.
| Area | Better | Why |
|---|
| Bass | A | Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf digs deeper - 35Hz against 45Hz. |
| What you buy | depends | KEF LS50 Wireless II is a complete system - just add a source. Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf also needs an amplifier: more money and another box, but you choose it. |
| Connections | depends | KEF LS50 Wireless II has Bluetooth, Wi-Fi, streaming and HDMI built in. With Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf that all comes from the amplifier you pair it with. |
| Upgrade path | depends | Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf can be re-amped later and outlive several amplifiers; KEF LS50 Wireless II ages as one unit. |
| Size | depends | KEF LS50 Wireless II is easier to place; Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf is bigger, which usually goes with fuller bass. Your room decides. |
| Expandability | B | KEF LS50 Wireless II: a sub output. |
| Price | evenly matched | Much the same money ($2,999 vs $2,999 a pair) - though the passive pair still needs an amplifier. |
A Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf 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 suits you if you want one box, ready to play, with nothing else to buy. Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf suits you if you already have an amplifier, want to choose the electronics, or expect to upgrade in stages. Neither is the better speaker in the abstract. 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, Aperion Grandis GR6 6.5" 2-Way High Fidelity Bookshelf 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.