hey guys so i am looking to build a new mixer soon, and as my core is coming to replace my arduino soon i thought i would give my arduino something to do and then later switch that for… another core 
but as i am new to audio i need a little advice on what is actually needed for my project and if an arduino/core can even run it. so here it goes,
i would like to create a TOSLINK mixer for my audio system, currently it seems to need the following;
INPUTS
4 TOSLINK - PC, TV, Blu-Ray, and a spare
4 3.5mm jack
OUTPUTS
4 3.5mm jacks and a TOSLINK
now to do this from what i have researched it will need to do the following,
4 TOSLINK recievers outputting to a switch ic controlled by the arduin/core
the switch output to an audio processor (currently TDA7439) - unsure what control this needs
the output of that to a DAC - unsure which but one of these
the output from this then gets sent to 2 PGA2311 volume controllers, these control 4 audio channels to 4 outputs, this would need to be controlled by the arduino/core and i will be using some slide potentiometers for the arduino/core to get volume levels to give a mixer feel
so back to the title, do we have any audiophiles or someone that know about audio that could help me with this? and if anyone is wondering, my headphones i was to use are a set of DT770 pro 80ohm headphones so i need the PGA2311 to run it directly as they are capable of up to 600ohm’s
Thanks in advance
Regards,
Jamie
P.S. the 4 3.5mm jack inputs will feed directly into the output of the DAC to be mixed with the audio outputs the PGA2311 reads as, as far as i know you are able to mix audio from different analog sources together, but please correct me if i am wrong