How to connect a power sub to ASL Wave AV-20

[sstcobra]

Can someone describe how to (or better yet, where to) make a connection for a powered subwoofer to one of these ASL block amps?

[MCH]

You'll have to use to use the high level input connectors of your powered sub amp. Hopefully it has this mode of connection. This means you run your speaker wires from your ASL block amps to the sub amp via the high level inputs first . Then from the sub amp out to your speakers. You adjust the crossover level on the sub amp to suit your needs.
hopefully this is clear