Think, setting a main to 'large' means that the channel's bass (NOT any LFE signal) will not be redirected to the sub (or other large-set output).

In other words (assuming there is a properly-set sub channel), the main output setting for 'large' or 'small' chooses whether to keep the entire frequency range in that channel, or redirect frequencies below the crossover frequency to another output. This has no impact on the LFE signal.

The LFE channel can carry the same low-frequency sound as the mains, or a completely independent signal that either complements the mains, or could be completely different. For instance, there could be explosion impact in the LFE channel while bass-heavy music is playing in the mains, with neither channel reproducing anything the other is. The LFE is mixed as a sixth (or seventh) channel.

So, the strict answer to your question depends on which speaker(s) you want the mains' lows coming from: the mains or the sub. Are the mains capable of reproducing everything you want to hear from them?

Larry
www.fineelectricco.com