LFE+Main or Just LFE?

The LFE+Main setting on your AVR or AV processor is one of the most misunderstood settings. 
Most AVRs have this explained in their manual but here it is again to make it clear.

When the AVR is set to:

LFE: the subwoofer plays the LFE channel (the x.1 in your multichannel track) and all the frequencies of the speakers which are set to "Small"
- this is the setting you want to use in 95% of the setups

LFE+Main: the subwoofer plays the LFE channel, all the frequencies of the speakers which are set to "Small", and the bass frequencies of the main speakers which are set to "Large"/"Full-range".
That means you have double bass as your main speakers and the subwoofer will cover the same frequencies depending on the crossover you set.

- In most rooms, LFE+Main is not the best solution, but worth a try if you do not listen very loud and maybe have some dips in the frequency response.