Hi Guys,
Thanks for continuing to help.
I'm now a bit confused by what it is confusing you.
When asked what is my main source of music, I took that to mean what am I used to so I described my home hifi setup. This is mainly flac files stored on an external drive feeding a Naim Unitiqute streamer.
The way I've been using the N3 is:
Flac files stored on a micro sd card with earphones connected to the N3 as you'd expect. I think it doesn't sound exactly smooth and is a bit harsh. (grainy wasn't a good description)
To test the functionality, I have a cable to connect from the N3 headphone socket to the Unitiqute (it is a streamer with a built in amplifier and numerous inputs). I also used a cable from the N3 headphone socket to a JBL portable speaker and finally, I tried the Bluetooth capability of the N3 by pairing it with the JBL portable speaker.
The flac files stored on the sd card used in the N3 are copies of the flac files stored on the external storage that feeds the home hifi. I reloaded these to the sd card yesterday in case there was an issue with the files on the card.
For use as a USB DAC, I have the same files on my laptop that I load into foobar 2000. I've downloaded the Cayin universal driver and selected it in Preferences in foobar as the "sound card". The N3 is connected to a USB port using the included USB-C cable and I'm listening to music with the earphones connected to the N3. It is badly distorted. I suspect a driver issue but I've re-installed it twice and it still doesn't work.
Does that clarify things or am I doing something a bit odd?