Volume of ST into DT and how to match their volume?

How do you do it? I don’t want to max ST volume pot as it introduces noise running into DT comp, so what I did is I sampled a kick from ST, set the ST volume knob to 2 o-clock (pointing exactly to the upper left corner of the display glass) and started increasing the volume of the audio in on DT so the sampled kick matched (by ear) the kick from the ST. It ended up on 100 volume for the audio in.
Note that track volume and sample / instrument volume were also matching on both the machines. I remember someone saying that the audio in on DT should be 40? What is the scientific way?

From another recent thread regarding DT / DN / Minilogue XD,
I think this may be helpful. From @tubefund and @Tchu


Thank you for the reference, much appreciated! What if the ST gets too noisy on full volume running into the DT comp? I use the comp on limiter
-like settings. Still good to know that the volume pots are actually attenuators. Will explore.