Yes. Me.
The “issue” is that norns is designed to take a +4dBu signal while a lot of devices only output at +0dBu.
All of this is due to the fact that line level is not one clear standard but more a collection of them.
You’d need a line-level preamp (a regular mic preamp would be sub-optimal due to impedance mismatch) such as the one found on a mixer.
EDIT: There are also dedicated boxes w/ fixed gain called line-level shifters that also enforce the signal to be balanced.
@zebra proposed this patch allowing the boosting of the input gain. There is also an open discussion on making this feature standard.
See also: my original analysis.