I was originally playing with a fixed setting of +8...
The "Overflow Handling: Clip Protection" setting may limit the possible positive gain.
Rocket Man (in the track based mode)
- not possible to adjust by +8 dB without causing clipping:
8 dB - 3.55 dB = 4.55 dB
If my calculation is correct, +4.55 dB multiplies the peak value by ~1.69
1.69 x 0.69 = ~1.17 aka ~117% (i.e. it would clip)
If you have Clip Protection set, the maximum possible positive gain is +3.22 dB => ~100% peak value.
However, this should make Rocket Man relatively a bit quieter than it would be when no fixed adjustment is set in the options, not louder.
Heaven Sent (in the track based mode)
- can be adjusted by +8 dB without causing clipping because the total gain change stays negative:
8 dB - 14.54 dB = -6.54 dB
I assume it shouldn't matter which output mode I'm using. Currently it is WASAPI, but I can try others.
I can't see how the selected output mode could affect the behavior. The signal processing happens before the output.
Have you tried to switch Volume Leveling off and simply adjust the volume slider by about 11 dB between the two tracks? I mean, maybe the measurement is not correct in this case and the perceptual difference is actually quite a bit less than about 11 dB.
Edit: MC's volume slider doesn't show dB values, but you can use the preamp setting in the Equalizer DSP.