Thank you.
The text file helped for another issue (Rating / RatingLove while it is still disappearing when both are at 0).
I thought it was a bit simpler but I guess I will try with the Virtual, it should work with the bitrate /sample rate etc fields in the Track information.
EDIT:
Found exactly what I wanted with Virtual :
Formula :
$Upper($RSplit(<URL>,.,1)), <Sample Rate>, <Bit Depth> bits, <Bitrate>, <Channels>, <Time>