I haven’t done that many captures yet, but have some observations on how to use the instrument and capture input 1 levels.
For pedals, you typically set the gain, tone and volume of the pedal in the context of a signal chain, getting it to do what you want it to do in terms of saturation, volume boost/cut (who ever cuts?) and tone. So when capturing the pedal, you likely want to keep the instrument and capture levels at 0dB so the resulting capture block behaves the same way as the real pedal did in the same signal chain. The capture will have the same gain/saturation and volume with the capture block parameters set at 0dB. Then you can tweak from there.
But capturing amps is different, they need to be set to have the right amount of headroom, and avoid digital clipping. I did a little testing, and found that QC clean amp models (like the Twin) have a default level of around -12dB and clip at around -6dB on the output when you turn them all the way up. That leaves 6dB of headroom on the output to avoid engaging the output limiters. A guitar with single coil pickups at input 1 (or return 1), is around -18dB or so. So to have your amp+cab capture normalized to be similar to a QC amp models, you’d might want a clean capture in level to be around -12dB and a distorted capture to be around -6dB. In most cases, you’d leave the instrument level at 0dB so that the capture block produces the same saturation as the amp.
When capturing pedals:
- Set the pedal gain, tone and volume the way you want it in the signal chain
- Move the pedal into the capture loop
- Set instrument level to 0dB
- Set capture in level to 0dB
- Capture - the gain, and volume of the capture block will match the original pedal in the signal chain
When capturing amps:
- Put the amp+cab+mic into the capture loop
- Set the the gain, tone and volume on the amp way you want it
- Position the mic on the cabinet to get the tone you want
- Set instrument level to 0dB so the amp gain staging will be the same in the capture
- Set capture in level to get the level meter to show -12dB for a clean amp and -6dB for a distorted amp
- Capture - the gain/saturation, and volume of the capture block will match the original amp, and will have levels and headroom similar to the QC amps.