Audio confusion - MKV & DTS passthru

[chefjeff1373]

I have just enough general knowledge with audio settings to be dangerous.
I am confused regarding Audio settings in Handbrake.
I have a Vizio 54" 3.0 HTIB with an added powered Subwoof. I am using PC
hdd for movies, PC optical for sound, VLC as playback software.

I searched the Handbrake forums and read the surround sound guide:
https://trac.handbrake.fr/wiki/SurroundSoundGuide

After reading the surroud sound guide I concluded that in order for me to
get separate bass with a 5.1 DTS source track I need the below settings:
MKV container
auto passthru = AC3 (ffmpeg)
Source = DTS 5.1
codec = DTS passthru
Is this correct? ... Am I on the right track? ... Is there a better way?

If I have a 5.1 file playing on my 3.1 HTIB will audio be sent to the non-existent
rear surround speakers, thus losing some of the sound track?
My goal is to get decent quality sound and a separate bass channel on my
3.1 setup, which may be upgraded to 5.1 in future.

[Smithcraft]

I don't know what the limitations are to your Vizio HTIB setup is. Does it not support DTS?

SC