You sure it doesn't have optical so you dont need a convertor? That would be the best usability wise, can use the headunit however you like then. Yes it would mean everything gets resampled by the headunit, but i couldn't really tell the difference.

Using a joying, I was able to plug a duok u2 into the usb on the headunit and use UAPP installed on the headunit with no resampling (measured it), worked just like on a phone.

 

You sure it doesn't have optical so you dont need a convertor?

Using a joying, I was able to plug a duok u2 into the usb on the headunit and use UAPP installed on the headunit with no resampling (measured it), worked just like on a phone.

Unfortunately this unit doesn't have optical out... and none I could find that did have optical that fit my car.

So I guess next best option then is to use the usb -> d10s via head unit route as you mentioned.

 

I prefer to use optical out to reduce probability of ground loops. I have read on some other threads that if you use USB DAC, then audio for phone calls does not work properly. I a currently using optical output from a Mekede DUDU7 head unit in one car and from an Eonon unit in another car. Both work well. Optical is going into DSP which then distributes to the amps and speakers.

 

As old mate mentioned, going the usb dac route might play havoc with phone calls.
I'd lean more towards converting the coax to optical, but I do lean more towards the everyday usability over minor differences in sound quality.
Convertors are cheap enough, try both ways and see if the hassle of usb dac and its compromises is worth it.

 

Is the quality loss using a converter really going to be much?

I don't really use phone calls that much, mainly text with Android auto. But tbh i can forego that.

I've realised my main problem with this head unit is it has a noise floor. Low volume hiss as soon as its on, doesn't increase with volume though. Not sure if it will go away if running through amps. Hopefully it does.

 

I wouldnt expect any quality loss from a coax to optical conversion, unless of course it is resampling it, say from 192 to 96. However, the spdif digital output from an Android headunit will be 44(or is it 48), whatever the Android operating system resamples all audio to so it isn't an issue here.

I'd try both, headunit coax converted to optical vs uapp and d10s via headunit usb.

Noise floor on the speaker outs? Might be present on the RCAs, but I imagine the digital will be clean.

 

Noise floor on the speaker outs? Might be present on the RCAs, but I imagine the digital will be clean.

Well this is running through factory connections, amp and speakers. Not sure where the noise would be coming from...

I'll try the converter first, it sounds the easiest...