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 | evenly matched | Much the same reach (56Hz vs 55Hz). |
| What you buy | depends | PSB Alpha AM3 is a complete system - just add a source. PSB Alpha C10 also needs an amplifier: more money and another box, but you choose it. |
| Connections | depends | PSB Alpha AM3 has Bluetooth and phono built in. With PSB Alpha C10 that all comes from the amplifier you pair it with. |
| Upgrade path | depends | PSB Alpha C10 can be re-amped later and outlive several amplifiers; PSB Alpha AM3 ages as one unit. |
| Size | depends | PSB Alpha AM3 is easier to place; PSB Alpha C10 is bigger, which usually goes with fuller bass. Your room decides. |
| Type | depends | A Powered Bookshelf against a Passive Center Channel - a different job rather than a better one. |
| Price | evenly matched | Much the same money ($449 vs $449 a pair) - though the passive pair still needs an amplifier. |
A PSB Alpha AM3 B PSB Alpha C10
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?
PSB Alpha AM3 suits you if you want one box, ready to play, with nothing else to buy. PSB Alpha C10 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. In a large or open-plan room, PSB Alpha C10 has the cabinet volume to fill it more easily; in a small room, near a wall or at desk distance, PSB Alpha AM3 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.