If you use your Helix as an audio interface to record your dry guitar signal via USB 7 and/or 8, you have probably noticed the resulting waveform in your DAW is really wimpy. That can be a pain if you need to do any visual edits, or work with pitch or time-align plug-ins such as Melodyne.
On the other hand, if you record your dry signal via an audio interface other than Helix (or normalize the Helix/USB recorded waveform to decent visual levels), you'll overdrive Helix Native's inputs. HXN is really really really picky about input levels, so it's easy to overdrive stuff, especially your amp gain. To make things worse, HXN's input meter is (to be polite) lacking.
In short, there's a tradeoff between getting levels you're used to seeing in your DAW vs levels that HXN requires .So....here's what I do:
1) I normalize my dry guitar recorded waveform to -18 dbFS. (Use whatever level you are used to, -12, -6, etc). If you record your dry guitar with an audio interface other than Helix USB, you can simply set you level so its not clipping the inputs (no DAW normalizing needed). This step is intended to provide a "healthy" waveform consistent with your other recorded waveforms.
2) Uh oh! Now your nice-looking waveform will overdrive HXN's input and your tone will suck! What to do? I place Hornet's TheNormalizer plug-in (cheap, $5) in front of HXN, set the desired level to -24 dBFS, and play the guitar track to automatically set the level (or just play the section with peaks). You can use whatever plugin you want, or simply use a meter. You can also use HXN's input meter settings, but I prefer to bring the level down before it hits HXN, and I leave the HXN input level set to 0 dB. The main thing is to make sure the peaks you see in HXN's input don't go above -24. The manual says up to -12 is OK, but my experiments indicate that's too high.
3) Set HXN output level as desired for subsequent plug-ins or DAW level setting.