My psr-e453 has this nice future that they call it "USB audio" via "usb to host" port and I really miss this at my new s770.
It was a useful future for me, as I could record audio sound at my android tablet straightly and I could share it with just 1-2 clicks. Also I was using this to play music from the tablet to the keyboard instead of using the analog audio input of the keyboard. The good thing with the usb audio was that the sound was clean and it had zero noise background from the tablet, as opposite to the headphone jack audio output, that it produce a small but annoying buzz sound, when the tablet goes to sleep mode.
I understand that this is a certainly new future, as it came with the psr-e453 model, so the older psr-s770/s970 had not this function back in 2015, but what I don't understand is, why Yamaha didn't include this function at the new psr-s line keyboards of 2018.
Is it because they finally didn't change a thing at the circuit of these units and they just upgraded them with some more software futures only or finally the usb audio funtion has no future at all?