@User , the backannotation works if the circuit you have simulated is opened in xschem as top level and not descended into from a higher hierarchy. is this the case?

Yes that was indeed one of the problems and the top-level

ngspice_probe

annotations work when I click "Backannotate" but when I descend into the amp the

ngspice_probe

symbols in there still show a

?

. Why might that be do you think?

subcircuit nodes should be annotated to ngspice_probe in subcircuits. Nodes that can NOT be annotated in subcircuits are the symbol i/o ports, since these nodes are available at the parent level. Internal (local) nodes should work. If you can't get it working and if you have time and permissions to do so send me the test example, i can look at it.