Purchased the Jynxbox and was somewhat disappointed at first. The wifi antena is horrible, you want to use a cat 5 connection for this TRUST ME regardless what the box says your connection speed is, it is NOT!
Once you have it setup, immediately root it which you can do from the recovery screen. Careful, once your in the recovery screen, there is no way out of it till you root. So back everything up first.
Install MX Player, MX Player Codec arm6 & arm7
Launch MX PLayer, within settings select decoder: check mark S/W decoder (local, Network) Un-check S/W Audio. Now for CPU Core limit, set it to two as the Jynxbox is dual core. Color depth choose 16bit since we are using S/W decoding.
Now navigate to xbmxhub and locate the xbmc android download. Install this, and run it for the first time.
This should help you get the best 1080 resolution till someone tweaks XBMC to use hardware decoding on android.
Within Android settings, I specified the standard display screen size which for my gym screen its 720. I also set the Audio to RAW. This will help you TONS in regards to voice dropping out during playback.
Hope this helps,