@Dado ,
When the meters are at 0dB, the analogue output will be at +4dBu and the digital signal (USB) will be at around -18dBFS.
We do not boost the digital signal coming from the desk, as it would reduce headroom without any extra benefit. i.e. if boosted, you would increase the noisefloor and lose useful dynamic range.
This is because it’s a digital signal, so all the information is there already and you won’t be getting more information by boosting the signal before sending it to the DAW.
So if you need/want to increase the levels for recorded tracks, then it is best to normalise after recording, as you can always increase levels but you can’t get lost peaks back.
However, you can increase the direct out level by up to 10dB for each channel individually, in the ‘Routing’ screen (note the control is outside of the global direct out settings box). This will give you a increase in level by reducing the headroom to 8dB.
When streaming, where it’s not necessarily possible to increase levels later, you can make use of the mix compressor makeup gain to boost the signal too.
Most of this is covered here – https://support.allen-heath.com/Knowledgebase/Article/View/1121
Cheers,
Keith.
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