Have to say I’m blown away by the USB from the Pi4, I’ve had a Auralic Mini for a while now so well used to its USB output into my Mojo DAC, but the Pi4 simply let’s more through - the old veil lifted effect I suppose for want of a better phrase! I spent a long while making sure I wasn’t just listing to hardness or hash misinterpreted as detail, but no, the outlining and multi-stranded information is astonishing. Having said that, a bad recording quickly becomes unlistenable, but swapping the Mini for the Pi4 backwards and forwards on harsh tracks shows the issue is there in both cases.
Having said all that I am going to try a HAT board to check the Mojo’s other inputs as well, for those prices you would be daft not to play!
PS. The HiFiBerry article obviously plays up the need for a HAT still, understandably.