Speakers should be in phase when both are connected to their respective channels (Left, Right) with red to red, black-to-black at both the amp end and the speaker end. Reverse just one connection at either end (of either channel, but not both), and the speakers are out of phase,, which means when the left speaker's woofer is moving forward, the right one's woofer is moving the opposite direction. Putting the speakers face to face a few inches apart kills the bass so badly it is an eye-opening experience the first time experienced, try it. The effect is noticeable even if they aren't that close. Since your complaint is inadequate bass, everyone asked about phase for this reason.
The higher frequencies get 'phasey' too. They lose imaging and sound amorphous and non-directional when speakers are out of phase.
Positioning in the room makes or breaks bass, too, as some have noted. It is a matter of distance from walls, floor and ceiling - called boundary reinforcement - so don't discount out-of-hand the idea that positioning may be part of the issue. It makes a major contribution.
And break-in for new speakers can also make a significant contribution. New cones take a few hours to loosen up. You should reserve judgement until they've broken in. Playing them out of phase facing each other can hurry break-in time. Some speakers need more than others.
If you still don't like them after ensuring phase, room placement and some break-in time, then the question may become whether you can return them, possibly to exchange for a different brand or model. Good luck in your quest.
