Tidbits, If what you mean is hook your laptop to a home theater system with separate front and rear audio pairs plus center and subwoofer, you can do so by using the 3 jacks. You must use 3 pcs stereo 3.5mm to RCA cables and insert them to the 3 jacks. Then you must configure the jack nearest you as front speakers, the next jack as center/sub speaker out, and the last as rear speaker out. The left channel of the middle jack is for center and the right channel is for sub (White L /Red R). You can select headphone or speaker for the front, it does not matter, but you have to select rear speakers for the last jack, otherwise, if you select headphone, it will just duplicate the output of the front speaker.

Using this setup, you can use front jack for headphones and rear jack for stereo component system for a surround sound system. if you just want plain stereo using 2 pairs of outputs, then select headphone for the rear jack. And select quad speaker configuration. And also, if you want 5.1 channel, you must also select 5.1 speaker configuration for it to work.

I did some experimenting just now. I hooked up a pair of earphones to the headphone jack (nearest to you) and configured it as headphone. I then connected my Vox Soundbox mini to the line out jack (farthest from you) and configured also as headphone. Speaker configuration configured as stereo. Any sound played by the headphones, also plays in the vox amp. Laptop speakers disabled of course. If I configure the rear line out as rear speakers and select quad for the speaker configuration, In youtube videos, I get normal sound for the headphones but for the line out, the vocals are cancelled out so you only hear instruments or music. It's like a minus one track.

Try plugging it to front and rear jacks, set front and rear jacks as headphones. And select Quadrophonic for speaker setup. What you hear on your front headphones should also be duplicated by your rear headphones which I assume you will connect to an external amplifier. Note that the sound config will change settings after you click ok on the popup window when you connect your headphone.