Is the Depth 212 good for music or mainly movies?

Both, but its sealed dual-driver design is especially good for music. The bass is tight and quick rather than boomy, and it still handles movie effects well.

How does it compare with the SVS SB-3000?

Both are sealed subs with app or onboard tuning. The Depth 212 has two 12-inch drivers and a very quiet cabinet; the SVS is a single 13-inch design that typically costs less and plays a bit louder.

Does it need a special amplifier or receiver?

No. It has its own onboard amplifier, so you connect it to a receiver or preamp with a subwoofer or line output. It also has speaker-level inputs for systems without a sub out.

Can I use two Depth 212s in one room?

Yes. Two subs smooth out room modes and give more even bass across seats. The onboard controls let you match each one to the room.

The subwoofer, a power cord and the setup guide. Cables are not included, so plan on a subwoofer cable or speaker wire.

Is it worth it over a cheaper ported sub?

If you value tight, low-distortion bass and a compact cabinet, yes. If you mainly want maximum output for a large home theater, a big ported sub gives more for less.