GLM's AutoCal algorithm aims to give you a flat and neutral frequency response for your system. Therefore it also adjusts the level of your speakers, subwoofer(s) and the phase (AutoPhase). 

But of course you can manually edit these settings to your needs. If you're looking for more low end, this is how to do it:

Use the Sound Character Profiler (SCP). In GLM 4 you can find it in the menu "Group Preset". This profiler allows you to adjust the frequency response of your complete system in an easy way. There is one important thing to be aware of: In GLM 4.1 we introduced positive gain for some models. But our subwoofers DO NOT support this feature. 

This is why you will have to lower the midrange and the top-end. Keep the low-end at the linear level instead of boosting it with the low shelf filter. Try out the following setting as an example: Set the Profiler Preset of the Sound Character Profiler to Manual and use the High Shelf filter. Enter 100 Hz for the frequency and then change the gain, e.g. to -2 dB. The result is more low-end.

Try out different settings to adjust it to your needs. You can hear the effect immediately while you're editing the settings. Click confirm to use your adjustments.

You can also use different groups to compare settings. Just activate one of your groups, select Group Preset > Duplicate and open the Sound Character Profiler for the new group to edit the settings.