[nickr]

Passthrough (aka bitstreaming) passes untouched a digital audio stream to the next device in the audio chain - so if you have it plugged into an AVR, the AVR gets the untouched digital audio. If you are plugged direct to the TV, the TV gets the untouched audio.

There are various multichannel audio codecs associated with video files. The main ones you'll deal with are:

DTS and AC3 (aka DD) are lossily compressed formats maxing out at 5.1. They are common on DVD and are also present on many Blurays.

DTS-HD and Dolby TrueHD are lossless high definition formats with up to (and can exceed) 7.1. They aren't found on DVD but are common on Bluray.

My understanding is that FTV will passthrough lossy formats like DTS and AC3, but not high def formats like DTS-HD and TrueHD. If so, this is one of the disadvantages of using a cheap android machine when you could pay a little more and get an x86 machine that will do what you are after.

Than again many people are happy with 5.1 compressed formats. Every DTS-HD track is supposed to have an associated DTS core which is played when your equipment can't handle DTS-HD. I don't know whether I can tell the difference until I get a new amplifier after my earthquake repairs are finished.