I was told at a Guitar Center that the Stagepas 500 can’t be used with a powered subwoofer.  I’ve read a few comments in this forum that seem to imply that it is possible (using the Monitor Out Jacks?).  Which is correct?  I already own the subwoofer, and would like to make use of it.  Also, what would be a good alternate choice in that price range if the Stagepas would, in fact, not accomodate a subwoofer?

Technically speaking the MONITOR OUTPUTS on the StagePas 500 are +4dBu and full-range - nothing says you cannot connect them to a sub-woofer. Without knowing what sub-woofer you are talking about and what its capabilities are, it is difficult to make a recommendation.

For example, does your sub-woofer have a way to filter out frequencies, remember the MONITOR OUTPUTS of the StagePas mixer are full-range? You do not want your sub-woofer attempting to reproduce the same full-range signal as your mains (just common sense). Yes, you will still get extended low frequency content but at the price of muddying the rest of the frequency spectrum.

If, however, you have sub-woofer that has the necessary filter (crossover), nothing prevents you from connecting a sub-woofer to the Monitor Outputs of the StagePas 500.

Hope that is helpful.