In the monitor mixer of uTool, you can see each channel are reduced with -12dB. That’s a safe value, if every channel have full scale signal, this helps to avoid from the overloading of the headphone amp.
You can change that -12dB value to higher, (of course your responsibility depending on your source files) to set the right value without clipping.
In this case the headphone output can be louder, but that will not solve the problem, if you try to use with high impedance headphones, with high impedace headphones need to use external headphone amp.
About the “noise recording” can you please send me some sample of this recordings to the firstname.lastname@example.org email address with detailed description of the connected inputs and devices?