Siblings in JBL's Studio series, so they share a family sound. It comes down to size, output and price.
| Area | Better | Why |
|---|
| Bass | B | JBL Studio 6 Architectural 8IW digs deeper - 43Hz against 58Hz. |
| Amplifier needs | B | JBL Studio 6 Architectural 8IW is more sensitive (93dB vs 90dB), so it goes louder on the same amplifier. |
| Size | depends | JBL Studio 6 Architectural 8IW is easier to place; JBL Studio 665C is bigger, which usually goes with fuller bass. Your room decides. |
| Type | depends | A Passive Center Channel against a Passive In-wall - a different job rather than a better one. |
| Cabinet | depends | Ported vs In-wall. |
| Price | A | JBL Studio 665C is cheaper - $400 against $1,300, about 69% less; arguably a different class. |
A JBL Studio 665C B JBL Studio 6 Architectural 8IW
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: JBL Studio 6 Architectural 8IW measures better, JBL Studio 665C costs about about 3.3x the price% 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 58Hz anyway, which makes the cheaper JBL Studio 665C much easier to justify. In a large or open-plan room, JBL Studio 665C has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, JBL Studio 6 Architectural 8IW 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.