I got a new AQ USB type C adapter and successfully lock i5 with external DAC. However the DAC output makes no sound. I have already set i5 to USB mode :cry:

Yes. I use the one comes from i5. Maybe I need to buy another one to try.

Still not work after reinstalling new firmware.   Yes, my cabling from i5 to the DAC is" i5 > type C to micro USB adapter > OTG cable > standard A/B USB cable   The DAC works well with my mobile as source.  The only difference in cabling is without the "type C to micro USB adapter".  

  Still not work      Anyway, I will try to install the new firmware again tomorrow.

Tried again but still unable to lock.

Yes, I would like to use i5 as source feeding to an external DAC. My answers to your questions are as below: (1) and (2) I used the same USB cable. No adapter added when connected to other devices, but Type C adapter added for connection with i5. (3) 851N cannot lock with i5. Same for my old...

I think I have misunderstood the function of the new firmware. Is it that i5 cannot be digital source for the music to be played through an external DAC via USB connection?

For other devices (including mobile) which works OK, I connect to the "USB Audio In" near the bottom right-hand corner of your photo.  

Dear Andy, after upgraded to Firmware 2.2, I tried to connect i5 to my DAC through USB cable.  My DAC is Cambridge Audio 851N which is also a network streamer.  However, the DAC got no signal after the connection, but it works properly with USB connections with other devices (including my...

Dear Andy, thanks for your detailed report on the Tidal stuttering problem. I just wonder why the same problem does not occur when using mobile (including those with multiple core CPU) to play Tidal in Hi-fi quality.

Andy, for the problems on Tidal streaming and offline content, the possible cause is the version of Android used in i5.  According to Tidal website, HiFi Mode is only compatible with Android devices using version 4.4.4 or above.  However i5 uses version 4.4 only.