I wouldn't set any volume control to the max! You have to think in a sequential manner: source, bridge, & output device. Fortunately there are amplitude adjustments in each area
The
source is Hauptwerk with actually 3 volume adjustments: Individual audio group levels (i.e. Default) found in the Audio menu, then overall Volume & Trim as the subject of this thread.
The
bridge (in your case) is your MOTU AVB interface. It too has sliders and adjustments for volume as well as EQ, compression, and reverb!
The
output device could be a headphone amp, traditional stereo deck, powered speakers, etc. which also has its own volume controls.
Since output devices vary widely, you'll have to determine what works best for you. If you are satisfied with your current sound, I'd leave it be. If you experiment and want to turn up the MOTU volume, be sure to turn the HW volume down. Think of it as a balancing act.
NOTE: The Hauptwerk audio level display is connected to your ASIO driver used for your MOTU interface. If you overdrive the MOTU, the Hauptwerk display will go into the red along with hearing some ugly distortion.
My advice is to set the output device and MOTU volume levels at certain level and leave them alone. That level should be at your desired volume at full organ or maybe a tad higher, but with the HW Volume slider at 85 or 90. This way if you load a different sample set that needs to be turned up you have the capability to do so within easy reach. With it being at 100 you can only go down and not up so you'll have to resort to a different menu or the MOTU mixing software for adjustment.
Hope this helps,
Danny B.