It works the same as any other subwoofer. The 3.5 out is full range audio. The subwoofer filters everything out but the bottom low pass frequencies to whatever the user settings are on the subwoofer or in the audio settings of the projector. I’m sure the optical out would do the same thing, but the majority of subwoofers have analog inputs while it’s rarer to offer optical or digital coax inputs (unfortunately).I remain curious how this will practically work - isolate the LFE information from the incoming, digital HDMI audio signal, convert it to analog and sent it out via a 3.5mm adapter cable with an RCA subwoofer connector on the other end?
The addition of a subwoofer correctly dialed in will make the projector speakers much more viable as a primary audio setup for many. I’m sure it will never happen, but it would be great if Optoma would recommend specific subwoofers that are a good match in timbre with the speakers.