Is it appropriate to use a pair of professional speakers and a subwoofer for my karaoke singing?

Not appropriate.

Subwoofer usually performs better for music. For accompaniment music, there is no need to use a subwoofer, ordinary speakers (with three-way speakers) are basically enough.

If it is used in large squares, stages, etc., yes. For family karaoke, a subwoofer is basically not needed.