A little google research turned out that your devices soundcard is not well supported in Linux:
https://bugzilla.kernel.org/show_bug.cgi?id=95681
There are, however some people reporting various success by following the instructions there. But be warned,the Thread is huge and not every instruction there is followable on Endless, especially not those with patches for the kernel.
TL;DR
Try the following commands and see if you can get some audio output:
amixer cset name="DAC L2 Mux" "IF2 DAC"
amixer cset name="DAC R2 Mux" "IF2 DAC"
amixer cset name="Mono DAC MIXL DAC L2 Switch" 1
amixer cset name="Mono DAC MIXR DAC R2 Switch" 1
amixer cset name="SPK MIXL DAC L2 Switch" 1
amixer cset name="SPK MIXR DAC R2 Switch" 1
amixer cset name="SPKVOL L Switch" 1
amixer cset name="SPKVOL R Switch" 1
amixer cset name="SPOL MIX SPKVOL L Switch" 1
amixer cset name="SPOR MIX SPKVOL R Switch" 1