You have a modified 70s tube amp, cranked and in a box which is all single ended class A. You have an output to go into the clean channel of an amp and one for headphones with CabSim on. You can go into headphones at 1AM in the morning when your neighbours are asleep and get a cranked 70s amp sound from your guitar late at night.
It’s great for writing as you can go straight into a recording interface. Or should have smoulder someone else’s make of amp, you can go straight into the PA or the DI box and just use that as a backup.