Is the B6X loud enough for a small gig?

For a cafe, small bar or party of a few dozen people it is fine. For a loud band or a large hall you will want more output and a subwoofer.

Does it need a subwoofer?

For speech and acoustic sets, no. For dance music or anything bass-heavy, most owners add one because the column's low end is limited.

Can I stream music to it over Bluetooth?

Yes. It has Bluetooth and app control, so you can play backing tracks from a phone or tablet without a mixer.

Is the 800 W rating continuous power?

No. It is a peak figure for the Class-D amplifier. Expect considerably less continuous output in real use.

What inputs and outputs does it have?

It has a built-in microphone plus a 1/8-inch headphone jack for monitoring. Check the connection panel for the exact mic and line inputs before buying.

How does it compare with a standard powered PA speaker?

It is easier to carry and covers a room more evenly, but a conventional two-way box usually gives more bass and a sturdier cabinet for the same outlay.