This is hardcore, apparently:
In this chapter we’ll simulate the diode clipper circuit from theXyceTMUsers’ Guide[1] bydrawing the circuit in gschem, generating a netlist using gnetlist, running a simulation in Xyce, and finally plotting the results in gnuplot.
Really, it's half as bad as you might think. But you only get to that after
installing all the pieces...
To be fair, they also have a decent documentation on that, it's just so much of it!
Doing it the second time it worked out half decent, only the "faster" multi-core simulation is now s l o w a s f?!
Quite happy with it aside from that. I packed the VM down to a bit over 4gb (from 20gb initially),
maybe I find a place to put it up for download.
Edit: It is definitely a bit more cumbersome than LTSpice, but also mightier. Not sure if it's (simulation speed is) faster...
There is qucs-s that hides all that but I am not sure on how well it actually works.