Those PSB GB Speakers need time to break in. I would run them continuously for 8-12 hours a day for about a week and let the woofers break in. They are not going to give you deep bass. What they will give you is nice tight mid bass. Also, the GB's should have bass ports, make sure that the ports do not have plugs in them. Many speakers with Ports including some PSB models come with foam port plugs that you can use to tighten up the bass but they also decrease the bass. Removing the plugs will give you more prominent bass.

If you have all the settings correct with the Onkyo receiver, it could be that the receiver just does not put out much bass or it could be your music source such as your CD, DVD player, computer or mp3 player. Also try speaker placement. Moving them to the corners of the room will help with bass.