Output is quite low in Amplitube 5

[CeltOnGuitar]

I'm using Amplitube 5 and have noticed i need to either boost the input to something like +12db or add a compressor right at the start and crank the volume up massively just to get any kind've ease of playing or decent sustain.

Without that i really have to play quite hard to get sufficient sound especially with legato playing...i have a very light touch in my playing and have no real issues in a normal hardware setup.

Have i got something wrong in the setup for this? I didn't add a noise gate pedal in the setup so it's not that. Unless there is a built in noise gate that we can't bypass on the input?

[R0lias-tg]

A couple of experiments you can try.
ONE
If you have a monitor knob on your USB interface turn it all the way to the Direct Injection side and see how good your natural sustain is with your rig. This is just a subjective hearing test on your side. You can try turning up the gain on the USB interface and see if you get a natural sustain more to your liking. I like to play the hardest level (of open chords) I'm going to play and have that tickle the -12 db led on mine, but that leaves a lot of headroom so you could go higher.
TWO
You can turn your monitor knob back to the DAW side if you want audible feedback but this test is purely visual.
Use the default AT5 preset and add the white NOISE GATE. I set mine so the LED is on solid when nothing is happening, and the lightest touch on the string makes the LED go off. For me that meant a threshold setting of -67dB. The release and depth don't really matter.

Put the metronome on 120 and hit play. When beat 1 comes around pluck the open high e string. When I do that with a moderate pluck the LED on the noise gate first flickers in measure 4 (around beat 2). So I'm getting a good six seconds+ of sustain. I tried this with the default amp on, and off, and it makes no difference.

I don't see a problem with boosting your input +12dB in AT5 if you like how the amp sounds but I suspect from a signal-to-noise perspective you want to have a good strong signal to start with (but avoid clipping). A higher input signal does have the advantage of then you might not need to boost the input on ALL amps. One convenient thing about the AT5 input boost slider is that setting does get saved with the preset.