Need to boost level of streaming audio

[sync]

I'm recording the audio that is being streamed in Media Player. The volume in the player is set to max. I'm recording from the monitor mixer of my MAudio Delta 66. All the volume controls in the monitor mixer are set to max.

When recording the peaks are about -18dB. Is there anything I can do to boost the signal level?

[TexRoadkill]

Add Gain, Normalize or Limit the waveform in an audio editing software.

[sync]

So you can't boost the level of the signal before it's recorded? Is that even that important when it's a digital signal?