As Tsutek suggests, first of all, always record @24bit. This will give you a signal to noise ratio of approximately 144db. Which basically means you can record at very low levels.
So given that fact, there is no reason to maximize master output on gear. The only thing you accomplish by setting master level to max is rendering that knob completely useless . A master level knob can be useful to occasionally compensate for preset sounds or projects that have a slightly higher/lower output volume than desired.
When you’ve set the master volume knob to 12 o clock. de-activate the Analog Heat, and also set the master volume on the heat to 12 o clock. Check the input meter on the Heat in the settings, and adjust the input gain until the peak volume (the loudest input volume) hits around 80% of the bar. Then check the Motu. adjust the input level so the peak doesn’t go above -12db. And this should refelect the input meter in your DAW as well.
Now set the wet level on the heat to 12 o’clock, and drive level fully counter clockwise, and dry/wet level fully clockwise. Select your desired circuit, lets say ‘saturation’. Activate the Heat. As you’ll probably notice the volume will drop significantly. Now start increasing the drive level and you’ll notice the volume increasing. When the drive level is at 12 o’clock de-activate the heat to check how the dry level compares to the wet level. re-activate the Heat and adjust the wet-level knob to match the dry level (de-activated heat state).
This is how you gain stage the heat properly. There is no volume drop if you do this properly. Sometimes I have the drive level very low, and the wet level fully clockwise to match the dry level. The dry/wet level is also a factor, and there’s also the filter drive AND the preset volume. So in case the wet level at its highest setting isn’t enough to match the level from a de-activated Heat, you can compensate that with preset volume.
Now if you have this under control, the only thing you need to do to keep everything in line is check the stages. If you have a preset on the analog4 that is lower in output than other presets, simply adjust the master output on the analog4 until the input level in the Heat settings hits 80% at its highest peaks. Alternatively, check if the motu hits around -12 db on the highest peaks.
This is why you should never maximize master volumes . Hope this helps!