Can I use both Line and Amp inputs at the same time?

It is not possible to be using both Line and Amp inputs at once.

On the Torpedo Live the Line input is designed to receive a guitar/bass preamplifier as a source, and it gets physically activated by plugging in the line — i.e., the jack itself disconnects the loadbox output (but the amp does remain loaded).

In other words, the Line input will cut the Amp-input signal as soon as you plug a jack into it, and you can only have one source going through the Torpedo Live.

For that reason you cannot have a jack plugged into the Line input if you wish to get the loadbox's signal out to your DAW or recorder.