If all the speakers are set to LARGE (or Full-Range), then each speaker would be sent all the bass that is encoded in each particular channel.
And, even though there may be a (scant) few processors that allow the LFE channel to be routed differently, almost all processors split and route the mono LFE channel to the front L/R speakers, solely, when configured as having no subwoofer connected.
Of course, it varies from soundtrack to soundtrack, but, yes, there CAN be "serious bass info" encoded in the surround channels of certain soundtracks.
It is not just the LFE channel that can contain really low info. All the other channels (including the surround channels) CAN have really low bass info encoded in them, too. When using bass management (i.e. SMALL), this info is routed to the subwoofer along with the LFE channel. If there is no subwoofer, then any low bass info from any speakers set to SMALL is routed, along with the LFE channel, to the front L/R speakers.
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